<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:d625b502-66a6-41fa-aa8d-d3a8004bc3a7,g:dc6dbe85-fde4-4b4e-b7eb-1fc59501bb98-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.wdc.com/role/ConsolidatedStatementsofConvertiblePreferredStockandShareholdersEquity" xlink:type="simple" xlink:href="wdc-20250627.xsd#ConsolidatedStatementsofConvertiblePreferredStockandShareholdersEquity"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ConsolidatedStatementsofConvertiblePreferredStockandShareholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_3dee7b51-114b-454a-b301-f0a4eac02e5d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_0437e6d1-e628-4151-853f-737f7774243b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_3dee7b51-114b-454a-b301-f0a4eac02e5d" xlink:to="loc_us-gaap_StatementTable_0437e6d1-e628-4151-853f-737f7774243b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_277dc62f-c707-4166-84f1-c093ea2fe82e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0437e6d1-e628-4151-853f-737f7774243b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_277dc62f-c707-4166-84f1-c093ea2fe82e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_277dc62f-c707-4166-84f1-c093ea2fe82e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_277dc62f-c707-4166-84f1-c093ea2fe82e" xlink:to="loc_us-gaap_EquityComponentDomain_277dc62f-c707-4166-84f1-c093ea2fe82e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_277dc62f-c707-4166-84f1-c093ea2fe82e" xlink:to="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_52c37a30-aba4-4684-906a-f1f832c336b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:to="loc_us-gaap_CommonStockMember_52c37a30-aba4-4684-906a-f1f832c336b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_2f8872dc-d3d4-47d3-8dc3-c6bf6c62c149" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:to="loc_us-gaap_TreasuryStockCommonMember_2f8872dc-d3d4-47d3-8dc3-c6bf6c62c149" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_424292be-5122-45c3-83b2-04bdd88bab10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_424292be-5122-45c3-83b2-04bdd88bab10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5731143b-9964-4e6d-9eef-3f2c3e27c322" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5731143b-9964-4e6d-9eef-3f2c3e27c322" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_efd80cc5-9212-42ca-85db-e7ebe691e98f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a8f7b11-a3ab-4452-bf34-47d02abb55ff" xlink:to="loc_us-gaap_RetainedEarningsMember_efd80cc5-9212-42ca-85db-e7ebe691e98f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ffaf5957-83a1-4740-8168-c7a945be5ab6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0437e6d1-e628-4151-853f-737f7774243b" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ffaf5957-83a1-4740-8168-c7a945be5ab6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ffaf5957-83a1-4740-8168-c7a945be5ab6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ffaf5957-83a1-4740-8168-c7a945be5ab6" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ffaf5957-83a1-4740-8168-c7a945be5ab6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d6d04bb7-031e-46ec-9b4d-9d9c3f06123a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ffaf5957-83a1-4740-8168-c7a945be5ab6" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d6d04bb7-031e-46ec-9b4d-9d9c3f06123a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_6b89557c-307a-4b5f-87d8-47302ef69660" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d6d04bb7-031e-46ec-9b4d-9d9c3f06123a" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_6b89557c-307a-4b5f-87d8-47302ef69660" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInTemporaryEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3dee7b51-114b-454a-b301-f0a4eac02e5d" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_95c1cf8a-4806-47cc-9372-892939b9e135" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_95c1cf8a-4806-47cc-9372-892939b9e135" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_70cb8201-74f1-4c8f-adba-da4759daa997" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_70cb8201-74f1-4c8f-adba-da4759daa997" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_df77ba99-4382-4c3a-810e-afbcf6ce9c38" xlink:href="wdc-20250627.xsd#wdc_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_wdc_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_df77ba99-4382-4c3a-810e-afbcf6ce9c38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_73c64c8c-b40f-4c40-8d34-890210287fc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_73c64c8c-b40f-4c40-8d34-890210287fc6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquitySharesConversionOfConvertibleSecurities_9533c23a-a658-4a7e-a845-a9decadf96fc" xlink:href="wdc-20250627.xsd#wdc_TemporaryEquitySharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_wdc_TemporaryEquitySharesConversionOfConvertibleSecurities_9533c23a-a658-4a7e-a845-a9decadf96fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquityValueConversionOfConvertibleSecurities_51afed2e-40f3-4749-b820-613e8bc00fb5" xlink:href="wdc-20250627.xsd#wdc_TemporaryEquityValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_95b38878-ef81-45dc-8bef-1ca23c03ad60" xlink:to="loc_wdc_TemporaryEquityValueConversionOfConvertibleSecurities_51afed2e-40f3-4749-b820-613e8bc00fb5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_bff6eb62-2da3-4937-b768-41db0a4cc72d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_dd48a688-961f-4374-9594-b2a4e5f4b6fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3dee7b51-114b-454a-b301-f0a4eac02e5d" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_e009a8bb-72ff-46d6-a84a-07fb7d0f3787" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_e009a8bb-72ff-46d6-a84a-07fb7d0f3787" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_daf2e90e-525d-495c-a645-9e81e39fd7d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockholdersEquity_daf2e90e-525d-495c-a645-9e81e39fd7d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_52725d2d-3d66-450a-9d2e-466dead08702" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_TreasuryStockCommonShares_52725d2d-3d66-450a-9d2e-466dead08702" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_c4faab0c-2ef9-49e6-b83a-e995bcf5fdc1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_NetIncomeLoss_c4faab0c-2ef9-49e6-b83a-e995bcf5fdc1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_AdjustmentsToAdditionalPaidInCapitalPurchaseOfCappedCalls_0f8e9c9f-e441-4f9f-af69-0d6aa27e976f" xlink:href="wdc-20250627.xsd#wdc_AdjustmentsToAdditionalPaidInCapitalPurchaseOfCappedCalls"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_wdc_AdjustmentsToAdditionalPaidInCapitalPurchaseOfCappedCalls_0f8e9c9f-e441-4f9f-af69-0d6aa27e976f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_fcef32e8-3a7e-4304-8465-a00e0a5c4ca3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_fcef32e8-3a7e-4304-8465-a00e0a5c4ca3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_deb893c3-7f10-4fcc-a7f4-1899699db0d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_deb893c3-7f10-4fcc-a7f4-1899699db0d4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteSpinoffTransaction_76522e4b-83b3-495a-974c-10b5c46a9203" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityNoteSpinoffTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockholdersEquityNoteSpinoffTransaction_76522e4b-83b3-495a-974c-10b5c46a9203" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_c0918038-8668-4fc5-b15b-029d2cac4f0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_c0918038-8668-4fc5-b15b-029d2cac4f0a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_StockIssuedDuringPeriodValueIncreaseDecreaseForEmployeeStockPurchasePlan_d0f2fea4-2c87-4a31-b9f5-6da1d705878f" xlink:href="wdc-20250627.xsd#wdc_StockIssuedDuringPeriodValueIncreaseDecreaseForEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_wdc_StockIssuedDuringPeriodValueIncreaseDecreaseForEmployeeStockPurchasePlan_d0f2fea4-2c87-4a31-b9f5-6da1d705878f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2b38c081-8d2e-4647-a067-c91b74e950ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2b38c081-8d2e-4647-a067-c91b74e950ca" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_01f14104-d2e7-4013-984a-da0f9fd75d8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_01f14104-d2e7-4013-984a-da0f9fd75d8f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_d4bb719f-c6c0-4cba-9e97-c26e80ce5678" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_d4bb719f-c6c0-4cba-9e97-c26e80ce5678" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_43ba0d8d-a74a-4fad-8812-9145b20a1e6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_DividendsPreferredStockCash_43ba0d8d-a74a-4fad-8812-9145b20a1e6a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_16dd2d7f-891d-459a-887c-a6b98d7bb429" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_DividendsCommonStock_16dd2d7f-891d-459a-887c-a6b98d7bb429" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_c0927c3a-62c3-4844-af2f-d1960e8a614d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_c0927c3a-62c3-4844-af2f-d1960e8a614d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_b054f884-3810-498a-92cc-44e9ad424bab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_b054f884-3810-498a-92cc-44e9ad424bab" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_0b08cde1-26ed-405f-a4f1-aa06c619ab96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2682ea4c-6fd8-4ddb-8c67-b79fca1875e9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_0b08cde1-26ed-405f-a4f1-aa06c619ab96" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_98f3fd32-4de3-4383-85c5-319e12c832ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_dda04d45-8637-4474-85b9-5fc350bde2a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_971d8c5b-842a-43cb-b858-8afcf0a1177e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/OrganizationandBasisofPresentationAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#OrganizationandBasisofPresentationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/OrganizationandBasisofPresentationAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_36f110ff-bbbe-4427-af6a-b8d302913e84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_36f110ff-bbbe-4427-af6a-b8d302913e84" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a4964911-9593-4b12-ad08-197df44d99dc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_36f110ff-bbbe-4427-af6a-b8d302913e84" xlink:to="loc_srt_RangeAxis_a4964911-9593-4b12-ad08-197df44d99dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a4964911-9593-4b12-ad08-197df44d99dc_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a4964911-9593-4b12-ad08-197df44d99dc" xlink:to="loc_srt_RangeMember_a4964911-9593-4b12-ad08-197df44d99dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f0e3867d-def5-40ec-94d4-3089e8930dbf" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a4964911-9593-4b12-ad08-197df44d99dc" xlink:to="loc_srt_RangeMember_f0e3867d-def5-40ec-94d4-3089e8930dbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_9c20f043-0786-4470-9ca9-1cdd27d5b9fb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f0e3867d-def5-40ec-94d4-3089e8930dbf" xlink:to="loc_srt_MinimumMember_9c20f043-0786-4470-9ca9-1cdd27d5b9fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_8edc7146-db03-4d31-8640-17ae697b4d01" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f0e3867d-def5-40ec-94d4-3089e8930dbf" xlink:to="loc_srt_MaximumMember_8edc7146-db03-4d31-8640-17ae697b4d01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_fbf8739d-48a5-4a57-9164-393e75b1748b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_36f110ff-bbbe-4427-af6a-b8d302913e84" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_fbf8739d-48a5-4a57-9164-393e75b1748b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_fbf8739d-48a5-4a57-9164-393e75b1748b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_fbf8739d-48a5-4a57-9164-393e75b1748b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_fbf8739d-48a5-4a57-9164-393e75b1748b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_5f4b4b42-acc1-4bee-a3dc-e030f19b71a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_fbf8739d-48a5-4a57-9164-393e75b1748b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_5f4b4b42-acc1-4bee-a3dc-e030f19b71a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InProcessResearchAndDevelopmentMember_e720f049-cc8a-482a-9907-6a6d0b57878f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InProcessResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_5f4b4b42-acc1-4bee-a3dc-e030f19b71a2" xlink:to="loc_us-gaap_InProcessResearchAndDevelopmentMember_e720f049-cc8a-482a-9907-6a6d0b57878f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_b1c3ce52-29c7-4758-847c-b96b8d349eed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_NumberOfReportableSegments_b1c3ce52-29c7-4758-847c-b96b8d349eed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_74911ed7-d17d-4fb3-aee6-52e5bcfdbad3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_74911ed7-d17d-4fb3-aee6-52e5bcfdbad3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_b9abe429-3579-494c-a9c1-23ddc9543790" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_b9abe429-3579-494c-a9c1-23ddc9543790" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ProductWarrantyTerm_d283f60b-aef1-4e5f-a466-e26921d16f3b" xlink:href="wdc-20250627.xsd#wdc_ProductWarrantyTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_wdc_ProductWarrantyTerm_d283f60b-aef1-4e5f-a466-e26921d16f3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_81d908e1-ffa9-452f-ad2b-0d1fe69ec55b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_AdvertisingExpense_81d908e1-ffa9-452f-ad2b-0d1fe69ec55b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_76a1dbc4-bdb3-4979-89d6-3bf2d1e249a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_c51c65db-ed4b-4da7-8eee-206963693a91" xlink:to="loc_us-gaap_DerivativeNotionalAmount_76a1dbc4-bdb3-4979-89d6-3bf2d1e249a0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/OrganizationandBasisofPresentationPropertyPlantandEquipmentUsefulLifeDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#OrganizationandBasisofPresentationPropertyPlantandEquipmentUsefulLifeDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/OrganizationandBasisofPresentationPropertyPlantandEquipmentUsefulLifeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_d94e6ff5-b9b4-4606-af6d-93361b770bc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_71ef0613-4c03-41b8-8b9a-eb43a460d2c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_d94e6ff5-b9b4-4606-af6d-93361b770bc2" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_71ef0613-4c03-41b8-8b9a-eb43a460d2c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_9ed51107-dde3-4382-a8dc-7dd21380b562" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_71ef0613-4c03-41b8-8b9a-eb43a460d2c9" xlink:to="loc_srt_RangeAxis_9ed51107-dde3-4382-a8dc-7dd21380b562" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9ed51107-dde3-4382-a8dc-7dd21380b562_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_9ed51107-dde3-4382-a8dc-7dd21380b562" xlink:to="loc_srt_RangeMember_9ed51107-dde3-4382-a8dc-7dd21380b562_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ee81663e-e8c2-4647-8987-8271cae6a2ec" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_9ed51107-dde3-4382-a8dc-7dd21380b562" xlink:to="loc_srt_RangeMember_ee81663e-e8c2-4647-8987-8271cae6a2ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_30078e75-773d-4c0f-86d8-aeb560c167ca" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ee81663e-e8c2-4647-8987-8271cae6a2ec" xlink:to="loc_srt_MinimumMember_30078e75-773d-4c0f-86d8-aeb560c167ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_78083023-1763-457a-acd1-08b651698b0a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ee81663e-e8c2-4647-8987-8271cae6a2ec" xlink:to="loc_srt_MaximumMember_78083023-1763-457a-acd1-08b651698b0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_1cbd468d-c402-46a7-bb0d-1f037f70ddb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_71ef0613-4c03-41b8-8b9a-eb43a460d2c9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_1cbd468d-c402-46a7-bb0d-1f037f70ddb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1cbd468d-c402-46a7-bb0d-1f037f70ddb9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_1cbd468d-c402-46a7-bb0d-1f037f70ddb9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1cbd468d-c402-46a7-bb0d-1f037f70ddb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fe688b45-0d7f-4a49-b069-a16dc98b55d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_1cbd468d-c402-46a7-bb0d-1f037f70ddb9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fe688b45-0d7f-4a49-b069-a16dc98b55d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_e2abec2b-e35b-478e-9fa7-cc34cda0def3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fe688b45-0d7f-4a49-b069-a16dc98b55d1" xlink:to="loc_us-gaap_BuildingMember_e2abec2b-e35b-478e-9fa7-cc34cda0def3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_f456ca65-a1f2-492d-a1a9-91e0497d98cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fe688b45-0d7f-4a49-b069-a16dc98b55d1" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_f456ca65-a1f2-492d-a1a9-91e0497d98cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_67077947-fdc9-4906-b6f7-8294d1aee926" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fe688b45-0d7f-4a49-b069-a16dc98b55d1" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_67077947-fdc9-4906-b6f7-8294d1aee926" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_34211c73-7064-440d-be6a-d85850ad8081" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_d94e6ff5-b9b4-4606-af6d-93361b770bc2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_34211c73-7064-440d-be6a-d85850ad8081" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_555530dc-3b34-441a-9e6e-c369120d3309" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:to="loc_us-gaap_ConcentrationRiskTable_555530dc-3b34-441a-9e6e-c369120d3309" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_6b37bc37-bde8-4da2-a3e7-da0820b99bde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_555530dc-3b34-441a-9e6e-c369120d3309" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_6b37bc37-bde8-4da2-a3e7-da0820b99bde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6b37bc37-bde8-4da2-a3e7-da0820b99bde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_6b37bc37-bde8-4da2-a3e7-da0820b99bde" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6b37bc37-bde8-4da2-a3e7-da0820b99bde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_70528441-2164-4102-9994-5f27fcb02165" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_6b37bc37-bde8-4da2-a3e7-da0820b99bde" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_70528441-2164-4102-9994-5f27fcb02165" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_2ba6a3dd-0495-4209-ad33-d70c79570d3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_70528441-2164-4102-9994-5f27fcb02165" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_2ba6a3dd-0495-4209-ad33-d70c79570d3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_2ac245e6-3775-4267-89de-c406089d8c53" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_555530dc-3b34-441a-9e6e-c369120d3309" xlink:to="loc_srt_MajorCustomersAxis_2ac245e6-3775-4267-89de-c406089d8c53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_2ac245e6-3775-4267-89de-c406089d8c53_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_2ac245e6-3775-4267-89de-c406089d8c53" xlink:to="loc_srt_NameOfMajorCustomerDomain_2ac245e6-3775-4267-89de-c406089d8c53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_2ac245e6-3775-4267-89de-c406089d8c53" xlink:to="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerOneMember_c02f271c-4409-455a-9fc8-504d95a5fd51" xlink:href="wdc-20250627.xsd#wdc_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:to="loc_wdc_CustomerOneMember_c02f271c-4409-455a-9fc8-504d95a5fd51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerTwoMember_32936d8a-04db-44c7-b4a5-d8edd090a253" xlink:href="wdc-20250627.xsd#wdc_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:to="loc_wdc_CustomerTwoMember_32936d8a-04db-44c7-b4a5-d8edd090a253" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerThreeMember_eae3eb5f-ec95-4398-9812-7217d88e4867" xlink:href="wdc-20250627.xsd#wdc_CustomerThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:to="loc_wdc_CustomerThreeMember_eae3eb5f-ec95-4398-9812-7217d88e4867" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TopTenCustomersMember_703663b2-f537-41b5-9453-a9f6d8c1e4a6" xlink:href="wdc-20250627.xsd#wdc_TopTenCustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_34071d0f-4072-4199-bb93-39a671175936" xlink:to="loc_wdc_TopTenCustomersMember_703663b2-f537-41b5-9453-a9f6d8c1e4a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_960a234d-f97b-444f-90f8-ed252d747148" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_555530dc-3b34-441a-9e6e-c369120d3309" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_960a234d-f97b-444f-90f8-ed252d747148" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_960a234d-f97b-444f-90f8-ed252d747148_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_960a234d-f97b-444f-90f8-ed252d747148" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_960a234d-f97b-444f-90f8-ed252d747148_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f411c85a-5270-4673-89f8-629131ce201a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_960a234d-f97b-444f-90f8-ed252d747148" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f411c85a-5270-4673-89f8-629131ce201a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_f7b32cbf-5f93-4b47-8b8c-83d4b8517c25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f411c85a-5270-4673-89f8-629131ce201a" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_f7b32cbf-5f93-4b47-8b8c-83d4b8517c25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_6f1bebe7-8048-4b30-92ab-3880d483b98e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f411c85a-5270-4673-89f8-629131ce201a" xlink:to="loc_us-gaap_AccountsReceivableMember_6f1bebe7-8048-4b30-92ab-3880d483b98e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_3e24fe15-9d32-48ba-80ef-085c931b9c82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:to="loc_us-gaap_NumberOfReportableSegments_3e24fe15-9d32-48ba-80ef-085c931b9c82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_a3dbcb89-fbf9-48b1-9642-b1fb15f7b5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_a3dbcb89-fbf9-48b1-9642-b1fb15f7b5e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_78b91a9c-a6a6-4c39-a4f7-cbdcfcbc2e47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_78b91a9c-a6a6-4c39-a4f7-cbdcfcbc2e47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_cb70605d-856c-42c3-b0af-5c47eddfd6b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_5f73c708-5234-4271-b2ef-c62b312029d1" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_cb70605d-856c-42c3-b0af-5c47eddfd6b0" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskSegmentReportingInformationbySegmentDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskSegmentReportingInformationbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskSegmentReportingInformationbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_56d68523-15ab-44c9-8adf-f2bbbf14fb9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_56d68523-15ab-44c9-8adf-f2bbbf14fb9b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_e07bb6c2-0aba-4eea-970a-f2c7fea7812c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_56d68523-15ab-44c9-8adf-f2bbbf14fb9b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_e07bb6c2-0aba-4eea-970a-f2c7fea7812c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e07bb6c2-0aba-4eea-970a-f2c7fea7812c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e07bb6c2-0aba-4eea-970a-f2c7fea7812c" xlink:to="loc_us-gaap_SegmentDomain_e07bb6c2-0aba-4eea-970a-f2c7fea7812c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b052b10f-6f26-4ec8-be44-50b08b22bbad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e07bb6c2-0aba-4eea-970a-f2c7fea7812c" xlink:to="loc_us-gaap_SegmentDomain_b052b10f-6f26-4ec8-be44-50b08b22bbad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_HDDMember_71141646-134a-4d7c-bf78-df249f9467b0" xlink:href="wdc-20250627.xsd#wdc_HDDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b052b10f-6f26-4ec8-be44-50b08b22bbad" xlink:to="loc_wdc_HDDMember_71141646-134a-4d7c-bf78-df249f9467b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d4a5c992-7b49-45fc-bf35-cfc5063ac202" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d4a5c992-7b49-45fc-bf35-cfc5063ac202" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CostOfProductAndServiceSoldAdjusted_5a8469a1-cc54-4e4b-8cd9-388e4bf426a7" xlink:href="wdc-20250627.xsd#wdc_CostOfProductAndServiceSoldAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_CostOfProductAndServiceSoldAdjusted_5a8469a1-cc54-4e4b-8cd9-388e4bf426a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_9233bfe6-72f3-4f7c-88cb-e7e8b7f1c679" xlink:href="wdc-20250627.xsd#wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_9233bfe6-72f3-4f7c-88cb-e7e8b7f1c679" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SellingGeneralAndAdministrativeExpenseAdjusted_f91dde8c-a1a2-45d5-a61e-704a6e793a93" xlink:href="wdc-20250627.xsd#wdc_SellingGeneralAndAdministrativeExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_SellingGeneralAndAdministrativeExpenseAdjusted_f91dde8c-a1a2-45d5-a61e-704a6e793a93" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_GainLossFromLitigationSettlementAdjusted_bba64009-3e26-4741-bc4c-58bd6d553cd8" xlink:href="wdc-20250627.xsd#wdc_GainLossFromLitigationSettlementAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_GainLossFromLitigationSettlementAdjusted_bba64009-3e26-4741-bc4c-58bd6d553cd8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentCharges_b761e2cd-82d4-4ef1-84a8-9a513f713782" xlink:href="wdc-20250627.xsd#wdc_BusinessRealignmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_BusinessRealignmentCharges_b761e2cd-82d4-4ef1-84a8-9a513f713782" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_fe9407a4-754e-4e44-81db-f8adee57e1ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_ShareBasedCompensation_fe9407a4-754e-4e44-81db-f8adee57e1ee" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_StrategicAlternativeReviewExpense_9b85c17b-b9cf-4196-9e0d-bc263087c833" xlink:href="wdc-20250627.xsd#wdc_StrategicAlternativeReviewExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_wdc_StrategicAlternativeReviewExpense_9b85c17b-b9cf-4196-9e0d-bc263087c833" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_3749bcae-87b1-478b-beb0-a27b97209fd7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_3749bcae-87b1-478b-beb0-a27b97209fd7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_fa578d4f-9b55-4790-86a0-261219391488" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_fa578d4f-9b55-4790-86a0-261219391488" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_c46da8dc-2ff3-42ce-8c38-7cc24f202e26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_c46da8dc-2ff3-42ce-8c38-7cc24f202e26" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_6051e6bd-e30d-4b00-9e95-c6772d3685f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_OtherExpenses_6051e6bd-e30d-4b00-9e95-c6772d3685f9" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_4d247bf7-d6c1-4a15-966e-f8ab07f4c9e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_4d247bf7-d6c1-4a15-966e-f8ab07f4c9e5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_9bbb6ec5-529d-441d-bc11-bee6ad34d209" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_9bbb6ec5-529d-441d-bc11-bee6ad34d209" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_aedc5921-4d0b-475b-942f-3148c621666e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_a5374d6c-f605-4aa1-9d80-13d00c714b9e" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_aedc5921-4d0b-475b-942f-3148c621666e" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_bb3a4d9c-ee73-4864-92d5-01c3575e55b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_d132b509-16d2-433d-a2d4-5986aad2f8bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_bb3a4d9c-ee73-4864-92d5-01c3575e55b3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_d132b509-16d2-433d-a2d4-5986aad2f8bc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_48aa86be-4df5-4cdb-867b-a5e6a20d8757" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d132b509-16d2-433d-a2d4-5986aad2f8bc" xlink:to="loc_srt_ProductOrServiceAxis_48aa86be-4df5-4cdb-867b-a5e6a20d8757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_48aa86be-4df5-4cdb-867b-a5e6a20d8757_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_48aa86be-4df5-4cdb-867b-a5e6a20d8757" xlink:to="loc_srt_ProductsAndServicesDomain_48aa86be-4df5-4cdb-867b-a5e6a20d8757_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_82958e08-0461-4cec-85d7-fe86b28bd6fc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_48aa86be-4df5-4cdb-867b-a5e6a20d8757" xlink:to="loc_srt_ProductsAndServicesDomain_82958e08-0461-4cec-85d7-fe86b28bd6fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CloudMember_155c3913-4ec8-41f9-a41e-0405a1213bd0" xlink:href="wdc-20250627.xsd#wdc_CloudMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_82958e08-0461-4cec-85d7-fe86b28bd6fc" xlink:to="loc_wdc_CloudMember_155c3913-4ec8-41f9-a41e-0405a1213bd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ClientDevicesMember_6c878a1c-cb65-479b-b18e-cf02c8e57d9d" xlink:href="wdc-20250627.xsd#wdc_ClientDevicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_82958e08-0461-4cec-85d7-fe86b28bd6fc" xlink:to="loc_wdc_ClientDevicesMember_6c878a1c-cb65-479b-b18e-cf02c8e57d9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ConsumerMember_1886f997-f0c5-4667-9639-4532549c625c" xlink:href="wdc-20250627.xsd#wdc_ConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_82958e08-0461-4cec-85d7-fe86b28bd6fc" xlink:to="loc_wdc_ConsumerMember_1886f997-f0c5-4667-9639-4532549c625c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7c1d328f-f363-4a0b-a8ea-8fe7b437996b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_bb3a4d9c-ee73-4864-92d5-01c3575e55b3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7c1d328f-f363-4a0b-a8ea-8fe7b437996b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskRevenuebyGeographyDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskRevenuebyGeographyDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskRevenuebyGeographyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_9a168076-b05b-40e4-9010-88adf3427049" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_de5de704-63cc-4929-9bf5-169b73871b98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_9a168076-b05b-40e4-9010-88adf3427049" xlink:to="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_de5de704-63cc-4929-9bf5-169b73871b98" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_de5de704-63cc-4929-9bf5-169b73871b98" xlink:to="loc_srt_StatementGeographicalAxis_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0" xlink:to="loc_srt_SegmentGeographicalDomain_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_e575c0c6-7cf8-4d19-a86f-fa4cbad0e1d0" xlink:to="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_7fdb6059-38b1-4810-9720-2f4d5b9d22b3" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_country_US_7fdb6059-38b1-4810-9720-2f4d5b9d22b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_064fcde1-640a-4d2d-8eac-7822d8f06e29" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_country_CN_064fcde1-640a-4d2d-8eac-7822d8f06e29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_HK_cf5585d4-25dd-4e6f-932c-75c4cb8fef4b" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_HK"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_country_HK_cf5585d4-25dd-4e6f-932c-75c4cb8fef4b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestOfAsiaMember_0aba2445-6ac3-4b3c-ad44-8a1775a2c8fa" xlink:href="wdc-20250627.xsd#wdc_RestOfAsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_wdc_RestOfAsiaMember_0aba2445-6ac3-4b3c-ad44-8a1775a2c8fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_7f44d0cb-ba93-4fee-b193-cbce0dd29b12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_us-gaap_EMEAMember_7f44d0cb-ba93-4fee-b193-cbce0dd29b12" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_OtherMember_ce44d9a4-1541-431b-b393-e1ab8fbc07d8" xlink:href="wdc-20250627.xsd#wdc_OtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b2ba0cb3-0ab6-4315-b945-2b32ae98121d" xlink:to="loc_wdc_OtherMember_ce44d9a4-1541-431b-b393-e1ab8fbc07d8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f78b0700-7bcb-4a7f-a7eb-7226904d7f16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_9a168076-b05b-40e4-9010-88adf3427049" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_f78b0700-7bcb-4a7f-a7eb-7226904d7f16" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskLonglivedAssetsbyGeographyDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskLonglivedAssetsbyGeographyDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SegmentReportingDisaggregatedRevenueGeographicInformationandConcentrationsofRiskLonglivedAssetsbyGeographyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_e5812732-863d-4747-b842-fb9b9c5f6d90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_11000399-a8a0-4dee-841d-c1a33bdfa6d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_e5812732-863d-4747-b842-fb9b9c5f6d90" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_11000399-a8a0-4dee-841d-c1a33bdfa6d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_11000399-a8a0-4dee-841d-c1a33bdfa6d0" xlink:to="loc_srt_StatementGeographicalAxis_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e" xlink:to="loc_srt_SegmentGeographicalDomain_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_43d73eb7-4cbb-4b3d-9136-8a21b7ecc50e" xlink:to="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_f5ed7f61-e888-477a-bafa-e2c3e108a983" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_country_US_f5ed7f61-e888-477a-bafa-e2c3e108a983" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_MY_3890cd75-15ff-4f13-85ba-0b03b319fce5" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_MY"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_country_MY_3890cd75-15ff-4f13-85ba-0b03b319fce5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_1f1420dd-9d16-4844-bed2-e2732aaba15d" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_country_CN_1f1420dd-9d16-4844-bed2-e2732aaba15d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_TH_2c463d3e-3fd8-4065-a149-f526a3e09848" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_TH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_country_TH_2c463d3e-3fd8-4065-a149-f526a3e09848" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestOfAsiaMember_96923c72-c8e7-42a2-83bf-b1042bba2a44" xlink:href="wdc-20250627.xsd#wdc_RestOfAsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_wdc_RestOfAsiaMember_96923c72-c8e7-42a2-83bf-b1042bba2a44" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_f1749349-8482-4389-a58f-f2ccbbfcf1ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a58e2bf2-8eb3-4db4-86a5-e005487f71fc" xlink:to="loc_us-gaap_EMEAMember_f1749349-8482-4389-a58f-f2ccbbfcf1ec" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_493ab728-1a44-4670-9ed4-b7425cdaa635" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_e5812732-863d-4747-b842-fb9b9c5f6d90" xlink:to="loc_us-gaap_NoncurrentAssets_493ab728-1a44-4670-9ed4-b7425cdaa635" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DiscontinuedOperationsAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DiscontinuedOperationsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DiscontinuedOperationsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b7848c3c-989a-4b15-be46-9043e0637432" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b7848c3c-989a-4b15-be46-9043e0637432" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b7848c3c-989a-4b15-be46-9043e0637432_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b7848c3c-989a-4b15-be46-9043e0637432" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b7848c3c-989a-4b15-be46-9043e0637432_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be0adf6b-2e9b-4b88-b902-66f80e827ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b7848c3c-989a-4b15-be46-9043e0637432" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be0adf6b-2e9b-4b88-b902-66f80e827ef9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskSemiconductorCo.Ltd.Member_878177be-6f64-4010-a0d2-a968510867bf" xlink:href="wdc-20250627.xsd#wdc_SandiskSemiconductorCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be0adf6b-2e9b-4b88-b902-66f80e827ef9" xlink:to="loc_wdc_SandiskSemiconductorCo.Ltd.Member_878177be-6f64-4010-a0d2-a968510867bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SaleOfEquityInterestInSanDiskSemiconductorCo.Ltd.Member_5f5f0432-16c0-43c9-a6b7-a8583d951fa1" xlink:href="wdc-20250627.xsd#wdc_SaleOfEquityInterestInSanDiskSemiconductorCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be0adf6b-2e9b-4b88-b902-66f80e827ef9" xlink:to="loc_wdc_SaleOfEquityInterestInSanDiskSemiconductorCo.Ltd.Member_5f5f0432-16c0-43c9-a6b7-a8583d951fa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_d525b418-9acd-4da1-a090-1bd8591e7974" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_d525b418-9acd-4da1-a090-1bd8591e7974" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_d525b418-9acd-4da1-a090-1bd8591e7974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_d525b418-9acd-4da1-a090-1bd8591e7974" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_d525b418-9acd-4da1-a090-1bd8591e7974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_4c93a1ff-8f78-4f19-aa6e-f86790dc5efa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_d525b418-9acd-4da1-a090-1bd8591e7974" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_4c93a1ff-8f78-4f19-aa6e-f86790dc5efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_6cf79464-d775-42a3-91cb-38e8654737ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_4c93a1ff-8f78-4f19-aa6e-f86790dc5efa" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_6cf79464-d775-42a3-91cb-38e8654737ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f665a2b7-c019-486c-bf77-00c9e38fd3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_4c93a1ff-8f78-4f19-aa6e-f86790dc5efa" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f665a2b7-c019-486c-bf77-00c9e38fd3a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_3c386a48-d58a-4ea6-bcfa-9115d9c712e5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_3c386a48-d58a-4ea6-bcfa-9115d9c712e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3c386a48-d58a-4ea6-bcfa-9115d9c712e5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_3c386a48-d58a-4ea6-bcfa-9115d9c712e5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3c386a48-d58a-4ea6-bcfa-9115d9c712e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_d8c12d62-bdde-4be3-9caf-4a79b204c1b6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_3c386a48-d58a-4ea6-bcfa-9115d9c712e5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_d8c12d62-bdde-4be3-9caf-4a79b204c1b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskCorporationFlashMember_9d891a72-ae5c-4cfe-8b80-65191db66ceb" xlink:href="wdc-20250627.xsd#wdc_SandiskCorporationFlashMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d8c12d62-bdde-4be3-9caf-4a79b204c1b6" xlink:to="loc_wdc_SandiskCorporationFlashMember_9d891a72-ae5c-4cfe-8b80-65191db66ceb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SanDiskSemiconductorShanghaiCo.Ltd.Member_9be26c16-1549-4e8a-a545-e242665e6dc4" xlink:href="wdc-20250627.xsd#wdc_SanDiskSemiconductorShanghaiCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d8c12d62-bdde-4be3-9caf-4a79b204c1b6" xlink:to="loc_wdc_SanDiskSemiconductorShanghaiCo.Ltd.Member_9be26c16-1549-4e8a-a545-e242665e6dc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_37ef744f-e0e1-4a91-8183-ff83fb580773" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_srt_RangeAxis_37ef744f-e0e1-4a91-8183-ff83fb580773" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_37ef744f-e0e1-4a91-8183-ff83fb580773_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_37ef744f-e0e1-4a91-8183-ff83fb580773" xlink:to="loc_srt_RangeMember_37ef744f-e0e1-4a91-8183-ff83fb580773_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_76b3dfed-468e-4b62-8495-df8fdd133540" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_37ef744f-e0e1-4a91-8183-ff83fb580773" xlink:to="loc_srt_RangeMember_76b3dfed-468e-4b62-8495-df8fdd133540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_67424412-a756-4d46-a7f6-c3bdb3839ae3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_76b3dfed-468e-4b62-8495-df8fdd133540" xlink:to="loc_srt_MaximumMember_67424412-a756-4d46-a7f6-c3bdb3839ae3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_b91946de-1349-430e-b742-91d042317196" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_us-gaap_DebtInstrumentAxis_b91946de-1349-430e-b742-91d042317196" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b91946de-1349-430e-b742-91d042317196_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_b91946de-1349-430e-b742-91d042317196" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b91946de-1349-430e-b742-91d042317196_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_84736f35-c62d-431f-bcee-b7dae11840f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_b91946de-1349-430e-b742-91d042317196" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_84736f35-c62d-431f-bcee-b7dae11840f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanBFacilityMember_1930d510-cd42-4c20-9374-f667133b6a99" xlink:href="wdc-20250627.xsd#wdc_TermLoanBFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_84736f35-c62d-431f-bcee-b7dae11840f9" xlink:to="loc_wdc_TermLoanBFacilityMember_1930d510-cd42-4c20-9374-f667133b6a99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_f36f62b8-04f2-4312-82b1-7581eb2e6e53" xlink:href="wdc-20250627.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_84736f35-c62d-431f-bcee-b7dae11840f9" xlink:to="loc_wdc_TermLoanA3Member_f36f62b8-04f2-4312-82b1-7581eb2e6e53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_us-gaap_CreditFacilityAxis_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94" xlink:to="loc_us-gaap_CreditFacilityDomain_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_9fcf3079-aa4a-4431-81b2-7f9662928964" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_c47c1904-5fdc-4f12-9e5a-b81b8bfb2a94" xlink:to="loc_us-gaap_CreditFacilityDomain_9fcf3079-aa4a-4431-81b2-7f9662928964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c1676e8f-37ee-42ba-8697-be76e45ab53b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9fcf3079-aa4a-4431-81b2-7f9662928964" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c1676e8f-37ee-42ba-8697-be76e45ab53b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_d06cbfc8-e392-45cc-b950-53a571ba2295" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a04170c-e296-4b7d-97be-e6f8cf5c06bf" xlink:to="loc_dei_LegalEntityAxis_d06cbfc8-e392-45cc-b950-53a571ba2295" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d06cbfc8-e392-45cc-b950-53a571ba2295_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_d06cbfc8-e392-45cc-b950-53a571ba2295" xlink:to="loc_dei_EntityDomain_d06cbfc8-e392-45cc-b950-53a571ba2295_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_c816e8b0-1d1f-4b17-9469-ed74c116670c" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_d06cbfc8-e392-45cc-b950-53a571ba2295" xlink:to="loc_dei_EntityDomain_c816e8b0-1d1f-4b17-9469-ed74c116670c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskCorporationFlashMember_08c204a0-f06b-40c0-a844-e63ac086be19" xlink:href="wdc-20250627.xsd#wdc_SandiskCorporationFlashMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_c816e8b0-1d1f-4b17-9469-ed74c116670c" xlink:to="loc_wdc_SandiskCorporationFlashMember_08c204a0-f06b-40c0-a844-e63ac086be19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_NumberOfIndependentPublicCompanies_2c337140-19a9-4dda-a9b4-47e249412884" xlink:href="wdc-20250627.xsd#wdc_NumberOfIndependentPublicCompanies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_NumberOfIndependentPublicCompanies_2c337140-19a9-4dda-a9b4-47e249412884" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EquityMethodInvestmentOwnershipPercentageSold_f8267600-eb04-42c7-b0b5-9f2ac7f2cf87" xlink:href="wdc-20250627.xsd#wdc_EquityMethodInvestmentOwnershipPercentageSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_EquityMethodInvestmentOwnershipPercentageSold_f8267600-eb04-42c7-b0b5-9f2ac7f2cf87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EquitySecuritiesFVNIOwnershipPercentage_15231bda-0651-4eb9-852e-285ab9acac28" xlink:href="wdc-20250627.xsd#wdc_EquitySecuritiesFVNIOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_EquitySecuritiesFVNIOwnershipPercentage_15231bda-0651-4eb9-852e-285ab9acac28" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal_50bdba76-2ae3-4767-abe7-22b9b1119276" xlink:href="wdc-20250627.xsd#wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal_50bdba76-2ae3-4767-abe7-22b9b1119276" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DebtExtinguishmentSharesGivenUp_82a498fc-a7d6-4ed4-92e5-665fbb2f3916" xlink:href="wdc-20250627.xsd#wdc_DebtExtinguishmentSharesGivenUp"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_DebtExtinguishmentSharesGivenUp_82a498fc-a7d6-4ed4-92e5-665fbb2f3916" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_60203ff5-77cd-4019-9d8f-1f020f8b4bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_60203ff5-77cd-4019-9d8f-1f020f8b4bd9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_82c65b7f-62e9-47ae-a9ad-4343953eb5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_82c65b7f-62e9-47ae-a9ad-4343953eb5f0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationPeriodOfContinuingInvolvementAfterDisposal_e7b1b2dc-a903-4c71-83ec-5051168ac3ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationPeriodOfContinuingInvolvementAfterDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_DiscontinuedOperationPeriodOfContinuingInvolvementAfterDisposal_e7b1b2dc-a903-4c71-83ec-5051168ac3ef" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_f65bd21b-fb8e-4af3-8ca9-375eb2eb9035" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_f65bd21b-fb8e-4af3-8ca9-375eb2eb9035" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_60117696-83ad-43fe-ab51-1375b7939066" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_60117696-83ad-43fe-ab51-1375b7939066" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_NumberOfBusinessVentureLegalEntities_d9cb7c1a-05b5-4aa6-b56f-e327c4421b3d" xlink:href="wdc-20250627.xsd#wdc_NumberOfBusinessVentureLegalEntities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_NumberOfBusinessVentureLegalEntities_d9cb7c1a-05b5-4aa6-b56f-e327c4421b3d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_2e055380-ea07-4c6c-82be-f34fc2cd77b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_2e055380-ea07-4c6c-82be-f34fc2cd77b1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_ec968af1-e53b-4f47-9907-9949961aa091" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_ec968af1-e53b-4f47-9907-9949961aa091" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_219bfa29-0237-4255-bca5-83b2888ddaa1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_219bfa29-0237-4255-bca5-83b2888ddaa1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SaleLeasebackTransactionNetCashProceeds_54b01a5e-c911-4d79-af5f-387e05187080" xlink:href="wdc-20250627.xsd#wdc_SaleLeasebackTransactionNetCashProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_wdc_SaleLeasebackTransactionNetCashProceeds_54b01a5e-c911-4d79-af5f-387e05187080" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleAndLeasebackTransactionGainLossNet_4c3773be-d7e3-4773-8f56-a2043826d4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SaleAndLeasebackTransactionGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_194e1f2c-65b6-462a-b25b-5b124906ab4e" xlink:to="loc_us-gaap_SaleAndLeasebackTransactionGainLossNet_4c3773be-d7e3-4773-8f56-a2043826d4e5" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DiscontinuedOperationsAssetsandLiabilitiesofDiscontinuedOperationsDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DiscontinuedOperationsAssetsandLiabilitiesofDiscontinuedOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DiscontinuedOperationsAssetsandLiabilitiesofDiscontinuedOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4539b380-cfe2-4691-bb89-fe6e94bfa698" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c3c1151f-71cd-4e43-a8db-7a3fa42322ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4539b380-cfe2-4691-bb89-fe6e94bfa698" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c3c1151f-71cd-4e43-a8db-7a3fa42322ed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_815ce495-0e54-443c-b49f-a421c41e79ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c3c1151f-71cd-4e43-a8db-7a3fa42322ed" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_815ce495-0e54-443c-b49f-a421c41e79ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_815ce495-0e54-443c-b49f-a421c41e79ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_815ce495-0e54-443c-b49f-a421c41e79ca" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_815ce495-0e54-443c-b49f-a421c41e79ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d5d87466-cbc8-480b-9735-16f5d4c385b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_815ce495-0e54-443c-b49f-a421c41e79ca" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d5d87466-cbc8-480b-9735-16f5d4c385b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskSemiconductorCo.Ltd.Member_c9116247-76dc-46c3-9afd-5d9bdae3eb0a" xlink:href="wdc-20250627.xsd#wdc_SandiskSemiconductorCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d5d87466-cbc8-480b-9735-16f5d4c385b4" xlink:to="loc_wdc_SandiskSemiconductorCo.Ltd.Member_c9116247-76dc-46c3-9afd-5d9bdae3eb0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_62f06d6d-ed0f-4856-ab37-f3940a77bb17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c3c1151f-71cd-4e43-a8db-7a3fa42322ed" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_62f06d6d-ed0f-4856-ab37-f3940a77bb17" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_62f06d6d-ed0f-4856-ab37-f3940a77bb17_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_62f06d6d-ed0f-4856-ab37-f3940a77bb17" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_62f06d6d-ed0f-4856-ab37-f3940a77bb17_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_7b896a31-ff90-4029-8e37-8ebf3401999b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_62f06d6d-ed0f-4856-ab37-f3940a77bb17" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_7b896a31-ff90-4029-8e37-8ebf3401999b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_66c0024f-f7dc-4c6b-9919-b8d07ba4816e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_7b896a31-ff90-4029-8e37-8ebf3401999b" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_66c0024f-f7dc-4c6b-9919-b8d07ba4816e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4539b380-cfe2-4691-bb89-fe6e94bfa698" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents_7659789a-451a-4da4-987e-2a3fe30872fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents_7659789a-451a-4da4-987e-2a3fe30872fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_dcb21616-b9c7-4625-80de-413f15397247" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_dcb21616-b9c7-4625-80de-413f15397247" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_6245841b-c42c-45b7-a69b-298283021537" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_6245841b-c42c-45b7-a69b-298283021537" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets_c692933d-7291-4677-82df-72a795b075ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets_c692933d-7291-4677-82df-72a795b075ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_69b21782-6265-42be-9540-d040374de4f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_69b21782-6265-42be-9540-d040374de4f5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_0723a5ec-e4c5-4dc3-a42a-be0865e7b987" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_0723a5ec-e4c5-4dc3-a42a-be0865e7b987" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyNotesReceivableAndInvestmentsNoncurrent_3baad02c-9217-47fb-bdfd-870339fe9ddd" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyNotesReceivableAndInvestmentsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyNotesReceivableAndInvestmentsNoncurrent_3baad02c-9217-47fb-bdfd-870339fe9ddd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_e0145916-b636-45e4-af73-f06f059ea1bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_e0145916-b636-45e4-af73-f06f059ea1bf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_27442511-e133-498c-a591-1ebeb793c4cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_27442511-e133-498c-a591-1ebeb793c4cc" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_36daf02c-3e7d-40be-a146-536b443fefbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract_0402355e-53ef-4550-b797-0be83a00fbb0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_36daf02c-3e7d-40be-a146-536b443fefbd" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4539b380-cfe2-4691-bb89-fe6e94bfa698" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_20f2138a-5c55-4027-819b-92de91b08f71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_20f2138a-5c55-4027-819b-92de91b08f71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyAccountsPayableCurrent_8a2d966d-d0c1-415f-8534-f31c0a9851b8" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyAccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationRelatedPartyAccountsPayableCurrent_8a2d966d-d0c1-415f-8534-f31c0a9851b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_00b9202d-621e-4079-baeb-f0c9665f2d7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_00b9202d-621e-4079-baeb-f0c9665f2d7c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedIncomeTaxesPayable_67cac7f0-6348-4c79-b568-e7edfd458d26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedIncomeTaxesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedIncomeTaxesPayable_67cac7f0-6348-4c79-b568-e7edfd458d26" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationAccruedCompensationCurrent_a0de98ee-b2f1-4454-b3a5-d3dd9dc264e1" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationAccruedCompensationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationAccruedCompensationCurrent_a0de98ee-b2f1-4454-b3a5-d3dd9dc264e1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_f9929973-edc9-47c2-937c-f6b7685c89ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_f9929973-edc9-47c2-937c-f6b7685c89ff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_b5c70d46-ac56-451d-82a6-f3e773b662bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract_a51affb2-72ac-4005-a2bc-c20a582d9cc0" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_b5c70d46-ac56-451d-82a6-f3e773b662bc" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DiscontinuedOperationsNetIncomeLossfromDiscontinuedOperationsNetofTaxesDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DiscontinuedOperationsNetIncomeLossfromDiscontinuedOperationsNetofTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DiscontinuedOperationsNetIncomeLossfromDiscontinuedOperationsNetofTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ff4ce49-d1cb-4b52-96da-f33c9e88714d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ff4ce49-d1cb-4b52-96da-f33c9e88714d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_5862b721-d531-4aa4-95b8-ebee54cc89fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ff4ce49-d1cb-4b52-96da-f33c9e88714d" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_5862b721-d531-4aa4-95b8-ebee54cc89fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_5862b721-d531-4aa4-95b8-ebee54cc89fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_5862b721-d531-4aa4-95b8-ebee54cc89fb" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_5862b721-d531-4aa4-95b8-ebee54cc89fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_31640a1a-8356-4514-bd41-2e51509fd623" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_5862b721-d531-4aa4-95b8-ebee54cc89fb" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_31640a1a-8356-4514-bd41-2e51509fd623" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_65fe51f2-5f9f-4dc1-a320-09b0f6a59b04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_31640a1a-8356-4514-bd41-2e51509fd623" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_65fe51f2-5f9f-4dc1-a320-09b0f6a59b04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fe873f2-5410-4f5c-aad9-4eb29024719e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ff4ce49-d1cb-4b52-96da-f33c9e88714d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fe873f2-5410-4f5c-aad9-4eb29024719e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3fe873f2-5410-4f5c-aad9-4eb29024719e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fe873f2-5410-4f5c-aad9-4eb29024719e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3fe873f2-5410-4f5c-aad9-4eb29024719e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbf3ad04-c31b-42c6-b865-b49bed2ec67f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fe873f2-5410-4f5c-aad9-4eb29024719e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbf3ad04-c31b-42c6-b865-b49bed2ec67f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskSemiconductorCo.Ltd.Member_4abc8eae-f612-4174-885c-e0656234cf1f" xlink:href="wdc-20250627.xsd#wdc_SandiskSemiconductorCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fbf3ad04-c31b-42c6-b865-b49bed2ec67f" xlink:to="loc_wdc_SandiskSemiconductorCo.Ltd.Member_4abc8eae-f612-4174-885c-e0656234cf1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_fd3be2b3-3cac-462f-a687-2875ed5f3ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_fd3be2b3-3cac-462f-a687-2875ed5f3ca8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_0bed7924-a7f2-4b07-b44f-f73e25c9b1ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_0bed7924-a7f2-4b07-b44f-f73e25c9b1ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopmentExpense_372d4c60-d6bc-4607-8294-76e293b0da77" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopmentExpense_372d4c60-d6bc-4607-8294-76e293b0da77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationSellingGeneralAndAdministrativeExpense_dc417692-7f0b-41df-bbdc-5f9cc3146403" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationSellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationSellingGeneralAndAdministrativeExpense_dc417692-7f0b-41df-bbdc-5f9cc3146403" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationGainLossOnDivestitureOfBusiness_324482cf-2355-4d1f-96d4-408d02ca5efa" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationGainLossOnDivestitureOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationGainLossOnDivestitureOfBusiness_324482cf-2355-4d1f-96d4-408d02ca5efa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationBusinessSeparationCosts_de2c9c4a-e2b1-4845-aa45-c1b380660163" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationBusinessSeparationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationBusinessSeparationCosts_de2c9c4a-e2b1-4845-aa45-c1b380660163" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationEmployeeTerminationAssetImpairmentAndOther_21a23ed9-ea5c-4b1b-a5ad-3420f7673f7e" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationEmployeeTerminationAssetImpairmentAndOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_ee068e31-7db2-444e-91bc-f2186f56dc72" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationEmployeeTerminationAssetImpairmentAndOther_21a23ed9-ea5c-4b1b-a5ad-3420f7673f7e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_24a1286f-444b-4764-963d-fad1f3479d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_24a1286f-444b-4764-963d-fad1f3479d9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense_bfc58c0b-2bba-4469-a089-5077f405ff44" xlink:href="wdc-20250627.xsd#wdc_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_wdc_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense_bfc58c0b-2bba-4469-a089-5077f405ff44" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_256c3845-ff16-4c99-a612-511e43b8351e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_256c3845-ff16-4c99-a612-511e43b8351e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_234de3de-4511-47ea-a4fd-5adb52cea37b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_234de3de-4511-47ea-a4fd-5adb52cea37b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_7d83c590-73cd-4a6a-8d4c-f3b0bceec857" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e114addd-c9cd-42c5-9688-df2a8dee918d" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_7d83c590-73cd-4a6a-8d4c-f3b0bceec857" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DiscontinuedOperationsSelectedCashFlowInformationfromDiscontinuedOperationsDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DiscontinuedOperationsSelectedCashFlowInformationfromDiscontinuedOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DiscontinuedOperationsSelectedCashFlowInformationfromDiscontinuedOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_9552f08e-49dd-4d00-8318-8bb2698c0c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ae4d9e9-7412-4f68-89b3-e80258ea125a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_9552f08e-49dd-4d00-8318-8bb2698c0c9a" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ae4d9e9-7412-4f68-89b3-e80258ea125a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_a9e1febe-f627-4a98-b6d1-b79b4ffa141c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ae4d9e9-7412-4f68-89b3-e80258ea125a" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_a9e1febe-f627-4a98-b6d1-b79b4ffa141c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_a9e1febe-f627-4a98-b6d1-b79b4ffa141c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_a9e1febe-f627-4a98-b6d1-b79b4ffa141c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_a9e1febe-f627-4a98-b6d1-b79b4ffa141c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_5f3fa083-5356-45c2-bf81-32a0e855e49e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_a9e1febe-f627-4a98-b6d1-b79b4ffa141c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_5f3fa083-5356-45c2-bf81-32a0e855e49e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_988dbd1d-1b3b-4d55-bb2a-aff4416bb4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_5f3fa083-5356-45c2-bf81-32a0e855e49e" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_988dbd1d-1b3b-4d55-bb2a-aff4416bb4ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9992f06e-3144-42ef-afe5-08ba6f6bb361" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_0ae4d9e9-7412-4f68-89b3-e80258ea125a" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9992f06e-3144-42ef-afe5-08ba6f6bb361" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9992f06e-3144-42ef-afe5-08ba6f6bb361_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9992f06e-3144-42ef-afe5-08ba6f6bb361" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9992f06e-3144-42ef-afe5-08ba6f6bb361_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b0773ffb-db22-49e9-b672-3791cf7aab8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9992f06e-3144-42ef-afe5-08ba6f6bb361" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b0773ffb-db22-49e9-b672-3791cf7aab8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskSemiconductorCo.Ltd.Member_39f72dfa-178a-4780-843f-32b634a93eea" xlink:href="wdc-20250627.xsd#wdc_SandiskSemiconductorCo.Ltd.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b0773ffb-db22-49e9-b672-3791cf7aab8f" xlink:to="loc_wdc_SandiskSemiconductorCo.Ltd.Member_39f72dfa-178a-4780-843f-32b634a93eea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_3f195b9c-f8db-4328-b51a-fedacd2482df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAndAmortizationDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_9552f08e-49dd-4d00-8318-8bb2698c0c9a" xlink:to="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_3f195b9c-f8db-4328-b51a-fedacd2482df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_0d94f65d-00c5-4de3-b42b-df0b1f02b5b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_9552f08e-49dd-4d00-8318-8bb2698c0c9a" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_0d94f65d-00c5-4de3-b42b-df0b1f02b5b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_d214cf58-bf20-4cb5-8d80-db3c13924060" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_9552f08e-49dd-4d00-8318-8bb2698c0c9a" xlink:to="loc_us-gaap_ShareBasedCompensation_d214cf58-bf20-4cb5-8d80-db3c13924060" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplementalFinancialStatementDataAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SupplementalFinancialStatementDataAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplementalFinancialStatementDataAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad82392d-b461-4b10-b9a4-d9b241a804d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad82392d-b461-4b10-b9a4-d9b241a804d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_093f233e-b4cd-4582-b1cf-d0b7ed596b44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad82392d-b461-4b10-b9a4-d9b241a804d5" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_093f233e-b4cd-4582-b1cf-d0b7ed596b44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_093f233e-b4cd-4582-b1cf-d0b7ed596b44_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_093f233e-b4cd-4582-b1cf-d0b7ed596b44" xlink:to="loc_us-gaap_ReceivableTypeDomain_093f233e-b4cd-4582-b1cf-d0b7ed596b44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_45de9b2a-78ce-4655-904b-f0f662e08024" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_093f233e-b4cd-4582-b1cf-d0b7ed596b44" xlink:to="loc_us-gaap_ReceivableTypeDomain_45de9b2a-78ce-4655-904b-f0f662e08024" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeAccountsReceivableMember_d7e5bac7-bed2-49bd-9a57-6f16dddfcfcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeAccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_45de9b2a-78ce-4655-904b-f0f662e08024" xlink:to="loc_us-gaap_TradeAccountsReceivableMember_d7e5bac7-bed2-49bd-9a57-6f16dddfcfcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bcadced6-bcec-40f9-8bc8-e65be7ea95df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad82392d-b461-4b10-b9a4-d9b241a804d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bcadced6-bcec-40f9-8bc8-e65be7ea95df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bcadced6-bcec-40f9-8bc8-e65be7ea95df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bcadced6-bcec-40f9-8bc8-e65be7ea95df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bcadced6-bcec-40f9-8bc8-e65be7ea95df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c04d4470-555c-4f03-be37-6a813c2d4e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bcadced6-bcec-40f9-8bc8-e65be7ea95df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c04d4470-555c-4f03-be37-6a813c2d4e1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InProcessResearchAndDevelopmentMember_12b189c8-9cfe-479b-adb9-378020ee1391" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InProcessResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c04d4470-555c-4f03-be37-6a813c2d4e1a" xlink:to="loc_us-gaap_InProcessResearchAndDevelopmentMember_12b189c8-9cfe-479b-adb9-378020ee1391" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_75fbb080-6fff-4fe2-8869-fcf0077598fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_ad82392d-b461-4b10-b9a4-d9b241a804d5" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_75fbb080-6fff-4fe2-8869-fcf0077598fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_75fbb080-6fff-4fe2-8869-fcf0077598fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_75fbb080-6fff-4fe2-8869-fcf0077598fc" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_75fbb080-6fff-4fe2-8869-fcf0077598fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_45b57102-372a-412c-8ee1-a257a526b77e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_75fbb080-6fff-4fe2-8869-fcf0077598fc" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_45b57102-372a-412c-8ee1-a257a526b77e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InProcessResearchAndDevelopmentMember_3fa8456a-b032-49c0-8465-e9961ddd97db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InProcessResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_45b57102-372a-412c-8ee1-a257a526b77e" xlink:to="loc_us-gaap_InProcessResearchAndDevelopmentMember_3fa8456a-b032-49c0-8465-e9961ddd97db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleAndCollectionOfReceivables_301564c7-663e-47f2-a82b-728c111ab5c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleAndCollectionOfReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_ProceedsFromSaleAndCollectionOfReceivables_301564c7-663e-47f2-a82b-728c111ab5c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_e5edd3a9-01fa-4a5e-b51e-ba392fb1e806" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_e5edd3a9-01fa-4a5e-b51e-ba392fb1e806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeReceivablesHeldForSaleAmount_9990ac7a-2080-4780-86e0-2fa0830ecf6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeReceivablesHeldForSaleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_TradeReceivablesHeldForSaleAmount_9990ac7a-2080-4780-86e0-2fa0830ecf6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_94c5567c-e718-47e7-8e12-4f7b37f413d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_Depreciation_94c5567c-e718-47e7-8e12-4f7b37f413d9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_c199cfe1-d0ef-4a5d-802f-96b8ca343ca3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_c199cfe1-d0ef-4a5d-802f-96b8ca343ca3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_ef1127fd-affb-47ef-be85-42400051d9a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_ef1127fd-affb-47ef-be85-42400051d9a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3f54bd87-0679-4e9e-b213-dbca5066c5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_Goodwill_3f54bd87-0679-4e9e-b213-dbca5066c5a3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_b0383794-9622-4656-b927-cce524eaef7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_2a373abd-a16b-49de-b217-0d4222a801e0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_b0383794-9622-4656-b927-cce524eaef7e" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplementalFinancialStatementDataPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SupplementalFinancialStatementDataPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplementalFinancialStatementDataPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SupplementalFinancialInformationLineItems_8fe53d55-9311-4761-848d-96a66295087e" xlink:href="wdc-20250627.xsd#wdc_SupplementalFinancialInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SupplementalFinancialInformationTable_6f4145f8-cb8f-43f2-a22b-c603b9e0b233" xlink:href="wdc-20250627.xsd#wdc_SupplementalFinancialInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_wdc_SupplementalFinancialInformationLineItems_8fe53d55-9311-4761-848d-96a66295087e" xlink:to="loc_wdc_SupplementalFinancialInformationTable_6f4145f8-cb8f-43f2-a22b-c603b9e0b233" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_6df09f30-162c-4af5-9cb0-c4aa23d78a0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_wdc_SupplementalFinancialInformationTable_6f4145f8-cb8f-43f2-a22b-c603b9e0b233" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_6df09f30-162c-4af5-9cb0-c4aa23d78a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6df09f30-162c-4af5-9cb0-c4aa23d78a0f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_6df09f30-162c-4af5-9cb0-c4aa23d78a0f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6df09f30-162c-4af5-9cb0-c4aa23d78a0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_6df09f30-162c-4af5-9cb0-c4aa23d78a0f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_d4eee028-f190-4ea6-b9c3-4410da514633" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_us-gaap_LandMember_d4eee028-f190-4ea6-b9c3-4410da514633" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_7216dc5f-9366-4821-86ae-c4fd69fe981a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_7216dc5f-9366-4821-86ae-c4fd69fe981a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_647cbd85-34fc-43bc-8ea7-f65c0c4d4089" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_647cbd85-34fc-43bc-8ea7-f65c0c4d4089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ComputerEquipmentandSoftwareMember_8007d7a1-e7d7-4e5a-9884-9c86982604ee" xlink:href="wdc-20250627.xsd#wdc_ComputerEquipmentandSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_wdc_ComputerEquipmentandSoftwareMember_8007d7a1-e7d7-4e5a-9884-9c86982604ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_d24e6e76-ad57-4518-87bb-8ee1bb1d59ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_d24e6e76-ad57-4518-87bb-8ee1bb1d59ce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_74b55737-ab60-460c-977a-d5e9a196c335" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5cc8e1eb-342f-4e23-982c-206af0f4d6ef" xlink:to="loc_us-gaap_ConstructionInProgressMember_74b55737-ab60-460c-977a-d5e9a196c335" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_c4addb33-4465-4e70-9510-f79c6a7dc5a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_SupplementalFinancialInformationLineItems_8fe53d55-9311-4761-848d-96a66295087e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_c4addb33-4465-4e70-9510-f79c6a7dc5a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_3f0bf7c7-f571-4c91-ac72-072a5b66b4d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_c4addb33-4465-4e70-9510-f79c6a7dc5a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_3f0bf7c7-f571-4c91-ac72-072a5b66b4d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_04e9bf2f-c8da-427a-8fe9-9fa80b1f9fe2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_c4addb33-4465-4e70-9510-f79c6a7dc5a2" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_04e9bf2f-c8da-427a-8fe9-9fa80b1f9fe2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_817e8367-b39b-4541-be9c-f47471ee924d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_c4addb33-4465-4e70-9510-f79c6a7dc5a2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_817e8367-b39b-4541-be9c-f47471ee924d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplementalFinancialStatementDataAccumulatedOtherComprehensiveLossRollForwardDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SupplementalFinancialStatementDataAccumulatedOtherComprehensiveLossRollForwardDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplementalFinancialStatementDataAccumulatedOtherComprehensiveLossRollForwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8f0f7098-e7b9-489f-851f-0066f24995d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_bfda4cac-8af9-4f38-ab03-92c4b46e20d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8f0f7098-e7b9-489f-851f-0066f24995d6" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_bfda4cac-8af9-4f38-ab03-92c4b46e20d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f051ee6e-e82b-43cf-af7d-4de43f4995f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_bfda4cac-8af9-4f38-ab03-92c4b46e20d0" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f051ee6e-e82b-43cf-af7d-4de43f4995f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f051ee6e-e82b-43cf-af7d-4de43f4995f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f051ee6e-e82b-43cf-af7d-4de43f4995f0" xlink:to="loc_us-gaap_EquityComponentDomain_f051ee6e-e82b-43cf-af7d-4de43f4995f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f051ee6e-e82b-43cf-af7d-4de43f4995f0" xlink:to="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_84cd8d96-1bf1-49a6-bd8d-c246cc53e623" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_84cd8d96-1bf1-49a6-bd8d-c246cc53e623" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_c00137b6-a515-4773-a3c8-2e0a62ccf901" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_c00137b6-a515-4773-a3c8-2e0a62ccf901" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_033e1578-e507-434d-acca-36c9a33efd71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_033e1578-e507-434d-acca-36c9a33efd71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_94676504-1731-4321-9899-bfd9462b838c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0291d2b4-023a-4b63-b2de-5c3a11f8e3f7" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_94676504-1731-4321-9899-bfd9462b838c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:href="wdc-20250627.xsd#wdc_AccumulatedOtherComprehensiveIncomeLossRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8f0f7098-e7b9-489f-851f-0066f24995d6" xlink:to="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_51928049-bdcc-4cb4-a27c-34fd48236e0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_us-gaap_StockholdersEquity_51928049-bdcc-4cb4-a27c-34fd48236e0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_308cdc3c-70b1-44df-ae73-01b5c2f8899a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_308cdc3c-70b1-44df-ae73-01b5c2f8899a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_6ca27816-e95c-4a67-9cfa-ac09cf831d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_6ca27816-e95c-4a67-9cfa-ac09cf831d2a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_dbf45cd6-4291-4d19-bd42-feb7d05212e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_dbf45cd6-4291-4d19-bd42-feb7d05212e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_aeefc15f-4a7b-4cc4-891b-313129842487" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_aeefc15f-4a7b-4cc4-891b-313129842487" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_StockholdersEquityNoteSpinoffTransactionAmountRecognizedInAccumulatedComprehensiveIncomeLoss_5a8ad795-c1ae-4597-b380-371c34e1aaef" xlink:href="wdc-20250627.xsd#wdc_StockholdersEquityNoteSpinoffTransactionAmountRecognizedInAccumulatedComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_AccumulatedOtherComprehensiveIncomeLossRollForward_ccd24763-85a4-49ae-b376-4e94f5f0a844" xlink:to="loc_wdc_StockholdersEquityNoteSpinoffTransactionAmountRecognizedInAccumulatedComprehensiveIncomeLoss_5a8ad795-c1ae-4597-b380-371c34e1aaef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_a4025cb5-770c-4684-a3eb-a7be9933b9f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetail" xlink:type="simple" xlink:href="wdc-20250627.xsd#FairValueMeasurementsandInvestmentsFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetail"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5695ebec-49aa-47f3-b6a3-0882f91e16e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5695ebec-49aa-47f3-b6a3-0882f91e16e0" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_6ac75bdc-5620-4233-bb3a-6bc18c6fade0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe5b9154-5c58-4d08-80ee-3f5fe0e4c04f" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_6ac75bdc-5620-4233-bb3a-6bc18c6fade0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_c03c317c-23b0-4e35-83e4-b7f63351c72b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_6ac75bdc-5620-4233-bb3a-6bc18c6fade0" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_c03c317c-23b0-4e35-83e4-b7f63351c72b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_aa2a2cb4-5084-4e92-a5e5-039568ccbafc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_aa2a2cb4-5084-4e92-a5e5-039568ccbafc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_aa2a2cb4-5084-4e92-a5e5-039568ccbafc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_aa2a2cb4-5084-4e92-a5e5-039568ccbafc" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_aa2a2cb4-5084-4e92-a5e5-039568ccbafc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8fed8de8-1a14-4214-b410-87c975c275d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_aa2a2cb4-5084-4e92-a5e5-039568ccbafc" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8fed8de8-1a14-4214-b410-87c975c275d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_38140d80-bf8c-49ed-8952-dee76a9ba097" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8fed8de8-1a14-4214-b410-87c975c275d2" xlink:to="loc_us-gaap_EquitySecuritiesMember_38140d80-bf8c-49ed-8952-dee76a9ba097" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_e4bd345f-cefe-4c5a-a2a2-cb69da30d2ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8fed8de8-1a14-4214-b410-87c975c275d2" xlink:to="loc_us-gaap_MoneyMarketFundsMember_e4bd345f-cefe-4c5a-a2a2-cb69da30d2ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_31ed4a87-7156-4094-8a0e-7de290cafcbb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8fed8de8-1a14-4214-b410-87c975c275d2" xlink:to="loc_us-gaap_ForeignExchangeContractMember_31ed4a87-7156-4094-8a0e-7de290cafcbb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_e28e7d0f-6719-4ba9-8f2e-3fec06b06103" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_e28e7d0f-6719-4ba9-8f2e-3fec06b06103" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_e28e7d0f-6719-4ba9-8f2e-3fec06b06103_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_e28e7d0f-6719-4ba9-8f2e-3fec06b06103" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_e28e7d0f-6719-4ba9-8f2e-3fec06b06103_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_c4ab20fa-34fa-437e-8354-b4df3ecce6ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_e28e7d0f-6719-4ba9-8f2e-3fec06b06103" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_c4ab20fa-34fa-437e-8354-b4df3ecce6ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_3246bf8e-46dc-4c10-92f6-e6095bf5e028" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_c4ab20fa-34fa-437e-8354-b4df3ecce6ed" xlink:to="loc_us-gaap_ForeignExchangeContractMember_3246bf8e-46dc-4c10-92f6-e6095bf5e028" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f804ac94-48b6-442b-86f6-ad3d80556195" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_32174b13-b530-4f46-8098-e524a7917f5c" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f804ac94-48b6-442b-86f6-ad3d80556195" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f804ac94-48b6-442b-86f6-ad3d80556195_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f804ac94-48b6-442b-86f6-ad3d80556195" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f804ac94-48b6-442b-86f6-ad3d80556195_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fca4a37c-fbc1-462a-b714-a9be0b5c36dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f804ac94-48b6-442b-86f6-ad3d80556195" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fca4a37c-fbc1-462a-b714-a9be0b5c36dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1d29d568-e591-4fb2-ade7-96a8836d99cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fca4a37c-fbc1-462a-b714-a9be0b5c36dc" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1d29d568-e591-4fb2-ade7-96a8836d99cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_652961a2-f146-4001-9be5-b24cace6923d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fca4a37c-fbc1-462a-b714-a9be0b5c36dc" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_652961a2-f146-4001-9be5-b24cace6923d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_4a74333a-a2b0-4157-a2cc-28534f077ff2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fca4a37c-fbc1-462a-b714-a9be0b5c36dc" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_4a74333a-a2b0-4157-a2cc-28534f077ff2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5695ebec-49aa-47f3-b6a3-0882f91e16e0" xlink:to="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_14d51edf-439c-46bf-946a-a713e233a5f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_14d51edf-439c-46bf-946a-a713e233a5f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_32b82468-52a4-4a74-8701-8f45146583c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_32b82468-52a4-4a74-8701-8f45146583c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_d40d7308-e6ad-4e31-9bf7-45a1ccefe87b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:to="loc_us-gaap_DerivativeAssets_d40d7308-e6ad-4e31-9bf7-45a1ccefe87b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_3a2f362a-2488-4efa-8d3a-18b9eab59a49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_21db2389-9ad7-4727-8ef4-0f69375e864e" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_3a2f362a-2488-4efa-8d3a-18b9eab59a49" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_a37f289f-0f1b-4c7f-abc2-cbc5b9287372" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5695ebec-49aa-47f3-b6a3-0882f91e16e0" xlink:to="loc_us-gaap_LiabilitiesAbstract_a37f289f-0f1b-4c7f-abc2-cbc5b9287372" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_ee74ea71-9cfc-4f8a-96e6-e2769ddb27d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_a37f289f-0f1b-4c7f-abc2-cbc5b9287372" xlink:to="loc_us-gaap_DerivativeLiabilities_ee74ea71-9cfc-4f8a-96e6-e2769ddb27d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_e80dc2e8-48b6-417f-a96c-88a181ca3864" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_a37f289f-0f1b-4c7f-abc2-cbc5b9287372" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_e80dc2e8-48b6-417f-a96c-88a181ca3864" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsNarrativeDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#FairValueMeasurementsandInvestmentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4b74cc89-2bdc-4bdb-9369-4a1d11a577f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3b6718e7-921b-4345-8993-ef6604ee1b72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4b74cc89-2bdc-4bdb-9369-4a1d11a577f3" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3b6718e7-921b-4345-8993-ef6604ee1b72" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_46fb8a9c-1711-4b6a-8f90-1c06e226532a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3b6718e7-921b-4345-8993-ef6604ee1b72" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_46fb8a9c-1711-4b6a-8f90-1c06e226532a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_46fb8a9c-1711-4b6a-8f90-1c06e226532a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_46fb8a9c-1711-4b6a-8f90-1c06e226532a" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_46fb8a9c-1711-4b6a-8f90-1c06e226532a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_fcfd57e3-d6ef-4d01-9012-c07b84bdc66b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_46fb8a9c-1711-4b6a-8f90-1c06e226532a" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_fcfd57e3-d6ef-4d01-9012-c07b84bdc66b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SandiskCorporationFlashMember_761d2856-ea44-416a-b222-7033673b01e3" xlink:href="wdc-20250627.xsd#wdc_SandiskCorporationFlashMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fcfd57e3-d6ef-4d01-9012-c07b84bdc66b" xlink:to="loc_wdc_SandiskCorporationFlashMember_761d2856-ea44-416a-b222-7033673b01e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3b6718e7-921b-4345-8993-ef6604ee1b72" xlink:to="loc_us-gaap_CreditFacilityAxis_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e" xlink:to="loc_us-gaap_CreditFacilityDomain_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_513092c2-c25d-41dd-820e-ccf2061ba3d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_82a4607e-c7a4-43e5-966e-c4b5e9f44f6e" xlink:to="loc_us-gaap_CreditFacilityDomain_513092c2-c25d-41dd-820e-ccf2061ba3d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_7f94f03b-9cb5-4f84-bfbf-f6c4bb97e1d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_513092c2-c25d-41dd-820e-ccf2061ba3d9" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_7f94f03b-9cb5-4f84-bfbf-f6c4bb97e1d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_3b6718e7-921b-4345-8993-ef6604ee1b72" xlink:to="loc_us-gaap_DebtInstrumentAxis_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8df5c72e-40d1-43e1-b0f5-ab3a92638b1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_6e717af2-2d98-4bb6-bdf8-55319ac1d7cb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8df5c72e-40d1-43e1-b0f5-ab3a92638b1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_661e041e-c3c8-459a-aa25-b229f344fc04" xlink:href="wdc-20250627.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8df5c72e-40d1-43e1-b0f5-ab3a92638b1c" xlink:to="loc_wdc_TermLoanA3Member_661e041e-c3c8-459a-aa25-b229f344fc04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal_22b5fe26-f561-4e87-b0d1-bacb15e70e1e" xlink:href="wdc-20250627.xsd#wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4b74cc89-2bdc-4bdb-9369-4a1d11a577f3" xlink:to="loc_wdc_DiscontinuedOperationEquitySecuritiesFVNIOwnershipInterestInSharesAfterDisposal_22b5fe26-f561-4e87-b0d1-bacb15e70e1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DebtExtinguishmentSharesGivenUp_fcb27194-1f85-488c-83c3-2f06a2fab35b" xlink:href="wdc-20250627.xsd#wdc_DebtExtinguishmentSharesGivenUp"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4b74cc89-2bdc-4bdb-9369-4a1d11a577f3" xlink:to="loc_wdc_DebtExtinguishmentSharesGivenUp_fcb27194-1f85-488c-83c3-2f06a2fab35b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_835a0e7d-23fb-4762-9f16-effc26ee8214" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4b74cc89-2bdc-4bdb-9369-4a1d11a577f3" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_835a0e7d-23fb-4762-9f16-effc26ee8214" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsDebtInstrumentFairValueDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#FairValueMeasurementsandInvestmentsDebtInstrumentFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsDebtInstrumentFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9b277542-c069-4f41-93a9-55e4b9e21a31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9b277542-c069-4f41-93a9-55e4b9e21a31" xlink:to="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_94266eb7-5f3f-4eae-a0fc-927989884854" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_94266eb7-5f3f-4eae-a0fc-927989884854" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_94266eb7-5f3f-4eae-a0fc-927989884854_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_94266eb7-5f3f-4eae-a0fc-927989884854" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_94266eb7-5f3f-4eae-a0fc-927989884854_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08366c02-d350-466f-9a05-8f7289492347" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_94266eb7-5f3f-4eae-a0fc-927989884854" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08366c02-d350-466f-9a05-8f7289492347" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_28e54b91-c048-4a40-baa8-ff6246e0ed48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_08366c02-d350-466f-9a05-8f7289492347" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_28e54b91-c048-4a40-baa8-ff6246e0ed48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_55a9334a-ca77-48a7-8ea0-1aa2c63d8888" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_55a9334a-ca77-48a7-8ea0-1aa2c63d8888" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_55a9334a-ca77-48a7-8ea0-1aa2c63d8888_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_55a9334a-ca77-48a7-8ea0-1aa2c63d8888" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_55a9334a-ca77-48a7-8ea0-1aa2c63d8888_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b84c8724-a7fa-4b5a-9777-a53b1d544e91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_55a9334a-ca77-48a7-8ea0-1aa2c63d8888" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b84c8724-a7fa-4b5a-9777-a53b1d544e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_18659697-e66d-465d-b260-acaf082457d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b84c8724-a7fa-4b5a-9777-a53b1d544e91" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_18659697-e66d-465d-b260-acaf082457d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_890ceb51-3fb2-4659-9969-fdb9ba52c6e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_18659697-e66d-465d-b260-acaf082457d6" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_890ceb51-3fb2-4659-9969-fdb9ba52c6e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_ff2e80bf-203e-41a6-84b8-365592d05576" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_18659697-e66d-465d-b260-acaf082457d6" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_ff2e80bf-203e-41a6-84b8-365592d05576" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_e5aa0796-17b9-41a7-870a-8c7f7a3b1925" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:to="loc_us-gaap_DebtInstrumentAxis_e5aa0796-17b9-41a7-870a-8c7f7a3b1925" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e5aa0796-17b9-41a7-870a-8c7f7a3b1925_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_e5aa0796-17b9-41a7-870a-8c7f7a3b1925" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e5aa0796-17b9-41a7-870a-8c7f7a3b1925_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_e5aa0796-17b9-41a7-870a-8c7f7a3b1925" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_6a149f9b-09f7-4329-8c8e-f806696c65d6" xlink:href="wdc-20250627.xsd#wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_6a149f9b-09f7-4329-8c8e-f806696c65d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA2Member_a1bb3a3a-dac2-48eb-ae93-524ae71e4e8a" xlink:href="wdc-20250627.xsd#wdc_TermLoanA2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_TermLoanA2Member_a1bb3a3a-dac2-48eb-ae93-524ae71e4e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_7cd36767-4254-481f-a122-144627a0c2f6" xlink:href="wdc-20250627.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_TermLoanA3Member_7cd36767-4254-481f-a122-144627a0c2f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ConvertibleNotesDue20283.00Member_b816761c-0bff-49f1-8b56-83195215b677" xlink:href="wdc-20250627.xsd#wdc_ConvertibleNotesDue20283.00Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_ConvertibleNotesDue20283.00Member_b816761c-0bff-49f1-8b56-83195215b677" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_fb3cf3b7-397d-46f3-b437-baf87ee13aed" xlink:href="wdc-20250627.xsd#wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_fb3cf3b7-397d-46f3-b437-baf87ee13aed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember_a70984e5-1379-4c84-9e12-8834905b3401" xlink:href="wdc-20250627.xsd#wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_42aaa243-4d01-4911-a8bc-008a8a7f7d32" xlink:to="loc_wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember_a70984e5-1379-4c84-9e12-8834905b3401" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_73b7c887-ee1d-4175-8f1e-8322f8e6fdca" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f53c96e2-c9a2-4115-b886-dec298bcf45e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6ddc89b4-ee04-41a0-9c7a-06a7ece3ddd4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f53c96e2-c9a2-4115-b886-dec298bcf45e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_cdcc513d-8f7d-4603-a82e-485448001cbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_f53c96e2-c9a2-4115-b886-dec298bcf45e" xlink:to="loc_us-gaap_ConvertibleDebtMember_cdcc513d-8f7d-4603-a82e-485448001cbf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_453530e8-c5a7-4dcf-8a14-43895353ec07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9b277542-c069-4f41-93a9-55e4b9e21a31" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_453530e8-c5a7-4dcf-8a14-43895353ec07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_24c96ccc-5398-436c-b33c-66f87f9d1d6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9b277542-c069-4f41-93a9-55e4b9e21a31" xlink:to="loc_us-gaap_LongTermDebtFairValue_24c96ccc-5398-436c-b33c-66f87f9d1d6d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DerivativeInstrumentsandHedgingActivitiesAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DerivativeInstrumentsandHedgingActivitiesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DerivativeInstrumentsandHedgingActivitiesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_b9cef1c4-6a36-4704-aae9-265e0453e80b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_03bf94b7-c5ff-4935-b2dc-6dc5c96be490" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_b9cef1c4-6a36-4704-aae9-265e0453e80b" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_03bf94b7-c5ff-4935-b2dc-6dc5c96be490" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_b09d59a1-023d-4ff1-ac3b-c96f993a2496" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_03bf94b7-c5ff-4935-b2dc-6dc5c96be490" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_b09d59a1-023d-4ff1-ac3b-c96f993a2496" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_b09d59a1-023d-4ff1-ac3b-c96f993a2496_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b09d59a1-023d-4ff1-ac3b-c96f993a2496" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_b09d59a1-023d-4ff1-ac3b-c96f993a2496_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_04fbd350-0ac6-445c-a9ca-30c371b184ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b09d59a1-023d-4ff1-ac3b-c96f993a2496" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_04fbd350-0ac6-445c-a9ca-30c371b184ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ForeignExchangeForwardContractsDesignatedMember_d66c9fbe-9818-4de9-95bc-db8ed5385cff" xlink:href="wdc-20250627.xsd#wdc_ForeignExchangeForwardContractsDesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_04fbd350-0ac6-445c-a9ca-30c371b184ec" xlink:to="loc_wdc_ForeignExchangeForwardContractsDesignatedMember_d66c9fbe-9818-4de9-95bc-db8ed5385cff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_35c1a469-1e43-473f-9fd7-f7e43ad64cea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_b9cef1c4-6a36-4704-aae9-265e0453e80b" xlink:to="loc_us-gaap_DerivativeTermOfContract_35c1a469-1e43-473f-9fd7-f7e43ad64cea" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DebtScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DebtScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_c077b763-88b0-4d5e-ab15-5015cef0fce5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_DebtInstrumentTable_c077b763-88b0-4d5e-ab15-5015cef0fce5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_4ffda0b2-bcb6-4f9c-ac06-ea8366153074" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c077b763-88b0-4d5e-ab15-5015cef0fce5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_4ffda0b2-bcb6-4f9c-ac06-ea8366153074" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4ffda0b2-bcb6-4f9c-ac06-ea8366153074_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4ffda0b2-bcb6-4f9c-ac06-ea8366153074" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4ffda0b2-bcb6-4f9c-ac06-ea8366153074_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_12cc4e50-48db-4d72-ac33-6c8fdbd72823" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4ffda0b2-bcb6-4f9c-ac06-ea8366153074" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_12cc4e50-48db-4d72-ac33-6c8fdbd72823" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_5464e89d-583e-4f74-87c7-d3f053f2bd08" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_12cc4e50-48db-4d72-ac33-6c8fdbd72823" xlink:to="loc_us-gaap_ConvertibleDebtMember_5464e89d-583e-4f74-87c7-d3f053f2bd08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_347ede50-28c7-4777-b98d-9613b1a007dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c077b763-88b0-4d5e-ab15-5015cef0fce5" xlink:to="loc_us-gaap_DebtInstrumentAxis_347ede50-28c7-4777-b98d-9613b1a007dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_347ede50-28c7-4777-b98d-9613b1a007dc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_347ede50-28c7-4777-b98d-9613b1a007dc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_347ede50-28c7-4777-b98d-9613b1a007dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_347ede50-28c7-4777-b98d-9613b1a007dc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_85435198-51a5-4460-8596-15c5b8f3188c" xlink:href="wdc-20250627.xsd#wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_85435198-51a5-4460-8596-15c5b8f3188c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA2Member_c73d5537-ac3a-415e-8f6f-4447e220fd33" xlink:href="wdc-20250627.xsd#wdc_TermLoanA2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_TermLoanA2Member_c73d5537-ac3a-415e-8f6f-4447e220fd33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_9a59feac-3609-4594-8904-bd3c458488cb" xlink:href="wdc-20250627.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_TermLoanA3Member_9a59feac-3609-4594-8904-bd3c458488cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ConvertibleNotesDue20283.00Member_77fefbfe-8479-4ded-b5cd-23f7a063e427" xlink:href="wdc-20250627.xsd#wdc_ConvertibleNotesDue20283.00Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_ConvertibleNotesDue20283.00Member_77fefbfe-8479-4ded-b5cd-23f7a063e427" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_d67e345a-10af-4989-b4a7-ba77e09b6953" xlink:href="wdc-20250627.xsd#wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_d67e345a-10af-4989-b4a7-ba77e09b6953" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember_29cc8dd8-6479-49f3-ade9-1b27a357e4cd" xlink:href="wdc-20250627.xsd#wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8d4a153-df4c-4eab-a4d8-ebd1db49c6e3" xlink:to="loc_wdc_ThreePointTenPercentSeniorNotesDueTwoThousandThirtyTwoMember_29cc8dd8-6479-49f3-ade9-1b27a357e4cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_29ed5ffb-b67e-44d9-a72f-af3ceab7b63e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_29ed5ffb-b67e-44d9-a72f-af3ceab7b63e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_4a308b72-9823-4a68-a17a-7318388563a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_4a308b72-9823-4a68-a17a-7318388563a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_b64e8e56-7fa3-4f7a-bab7-4db9d3d71d16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_b64e8e56-7fa3-4f7a-bab7-4db9d3d71d16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_c5d36b52-4bce-4d83-9b51-463d7a74ba06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_LongTermDebt_c5d36b52-4bce-4d83-9b51-463d7a74ba06" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_5153993b-0fb7-493e-ad6e-e317ab24d94b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_LongTermDebtCurrent_5153993b-0fb7-493e-ad6e-e317ab24d94b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_7a2d1ffe-21ec-4ea0-ae6f-c55a155606af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_aab39515-f0ed-4abc-a4f9-8604434bb240" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_7a2d1ffe-21ec-4ea0-ae6f-c55a155606af" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DebtAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#DebtAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DebtAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_4e4320cf-194f-4634-a142-40e8ea2da962" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_us-gaap_DebtInstrumentAxis_4e4320cf-194f-4634-a142-40e8ea2da962" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4e4320cf-194f-4634-a142-40e8ea2da962_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_4e4320cf-194f-4634-a142-40e8ea2da962" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4e4320cf-194f-4634-a142-40e8ea2da962_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_4e4320cf-194f-4634-a142-40e8ea2da962" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_a884218f-36b6-4039-816a-dd667cfe4ed6" xlink:href="wdc-20250627.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_TermLoanA3Member_a884218f-36b6-4039-816a-dd667cfe4ed6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RevolvingCreditFacility2027Member_10f40987-c343-4667-8230-da3bdf500a0e" xlink:href="wdc-20250627.xsd#wdc_RevolvingCreditFacility2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_RevolvingCreditFacility2027Member_10f40987-c343-4667-8230-da3bdf500a0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_8ea633c7-4a4c-44b3-9538-e3ede9832c87" xlink:href="wdc-20250627.xsd#wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_FourPointSeventyFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySixMember_8ea633c7-4a4c-44b3-9538-e3ede9832c87" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember_469e59ac-f4e3-4baf-a01d-aa1ca9083640" xlink:href="wdc-20250627.xsd#wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember_469e59ac-f4e3-4baf-a01d-aa1ca9083640" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_744d4157-6a86-42c9-9e48-7b1bc35a938a" xlink:href="wdc-20250627.xsd#wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_TwoPointEightyFivePercentSeniorNotesDueTwoThousandTwentyNineMember_744d4157-6a86-42c9-9e48-7b1bc35a938a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointHundredPercentSeniorUnsecuredNotesDueTwoThousandThirtyTwoMember_ba4d6914-adaf-4930-a7b9-844b8a1d5faa" xlink:href="wdc-20250627.xsd#wdc_ThreePointHundredPercentSeniorUnsecuredNotesDueTwoThousandThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_ThreePointHundredPercentSeniorUnsecuredNotesDueTwoThousandThirtyTwoMember_ba4d6914-adaf-4930-a7b9-844b8a1d5faa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA2Member_d77d3a58-9e89-4053-88f8-fc5c96bee8da" xlink:href="wdc-20250627.xsd#wdc_TermLoanA2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_TermLoanA2Member_d77d3a58-9e89-4053-88f8-fc5c96bee8da" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ConvertibleSeniorNotesDue2024Member_2674ae12-57e2-4250-b830-b61024aec4da" xlink:href="wdc-20250627.xsd#wdc_ConvertibleSeniorNotesDue2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1a5d3bef-4816-4db6-bf41-638caf2f3900" xlink:to="loc_wdc_ConvertibleSeniorNotesDue2024Member_2674ae12-57e2-4250-b830-b61024aec4da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_90bd727d-310f-43a9-9b81-48f5ca9ad570" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_us-gaap_CreditFacilityAxis_90bd727d-310f-43a9-9b81-48f5ca9ad570" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_90bd727d-310f-43a9-9b81-48f5ca9ad570_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_90bd727d-310f-43a9-9b81-48f5ca9ad570" xlink:to="loc_us-gaap_CreditFacilityDomain_90bd727d-310f-43a9-9b81-48f5ca9ad570_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_3a778ca7-5828-45a8-b33b-83007a2e8c22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_90bd727d-310f-43a9-9b81-48f5ca9ad570" xlink:to="loc_us-gaap_CreditFacilityDomain_3a778ca7-5828-45a8-b33b-83007a2e8c22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_d978b56c-ef24-463d-a51c-568a8f382f51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_3a778ca7-5828-45a8-b33b-83007a2e8c22" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_d978b56c-ef24-463d-a51c-568a8f382f51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_1727670c-3f85-45a9-ba8c-dfa70df9407c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_us-gaap_VariableRateAxis_1727670c-3f85-45a9-ba8c-dfa70df9407c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_1727670c-3f85-45a9-ba8c-dfa70df9407c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_1727670c-3f85-45a9-ba8c-dfa70df9407c" xlink:to="loc_us-gaap_VariableRateDomain_1727670c-3f85-45a9-ba8c-dfa70df9407c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_ac85dc8f-84b5-473e-b2a9-725a08c1030b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_1727670c-3f85-45a9-ba8c-dfa70df9407c" xlink:to="loc_us-gaap_VariableRateDomain_ac85dc8f-84b5-473e-b2a9-725a08c1030b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_1eff66dc-5913-441a-9f24-7d7294fd405b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_ac85dc8f-84b5-473e-b2a9-725a08c1030b" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_1eff66dc-5913-441a-9f24-7d7294fd405b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_0f184ca2-1c31-4318-8ecf-beef90ff6933" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_ac85dc8f-84b5-473e-b2a9-725a08c1030b" xlink:to="loc_us-gaap_BaseRateMember_0f184ca2-1c31-4318-8ecf-beef90ff6933" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_srt_RangeAxis_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d" xlink:to="loc_srt_RangeMember_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_322749a2-6467-4a28-b9bb-7c726e33a10c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5cee21e2-4b02-4f43-bcdd-6f08abb4b02d" xlink:to="loc_srt_RangeMember_322749a2-6467-4a28-b9bb-7c726e33a10c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f8662e9f-c150-48a9-be54-230f9a9face7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_322749a2-6467-4a28-b9bb-7c726e33a10c" xlink:to="loc_srt_MinimumMember_f8662e9f-c150-48a9-be54-230f9a9face7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_be27eefd-d237-4fc0-af36-21119bcb9934" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_322749a2-6467-4a28-b9bb-7c726e33a10c" xlink:to="loc_srt_MaximumMember_be27eefd-d237-4fc0-af36-21119bcb9934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d414be2a-5902-410e-b344-8d3ec214c568" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_69fb58ab-1be3-4cd4-bfe2-6db46cdad81d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d414be2a-5902-410e-b344-8d3ec214c568" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_434bf489-58aa-4c95-8b97-9d2b353bb7fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d414be2a-5902-410e-b344-8d3ec214c568" xlink:to="loc_us-gaap_SeniorNotesMember_434bf489-58aa-4c95-8b97-9d2b353bb7fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_c45b48db-6433-435c-a1f4-8d7cc3412b59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d414be2a-5902-410e-b344-8d3ec214c568" xlink:to="loc_us-gaap_ConvertibleDebtMember_c45b48db-6433-435c-a1f4-8d7cc3412b59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_afb6ec64-2b0e-4ac8-93ad-4e8829802bab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_079bf09c-ecb2-4728-93b9-7ac8b9fdfb85" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_afb6ec64-2b0e-4ac8-93ad-4e8829802bab" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_afb6ec64-2b0e-4ac8-93ad-4e8829802bab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_afb6ec64-2b0e-4ac8-93ad-4e8829802bab" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_afb6ec64-2b0e-4ac8-93ad-4e8829802bab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_eef880e8-5869-46e2-9f60-2ef931b1c935" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_afb6ec64-2b0e-4ac8-93ad-4e8829802bab" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_eef880e8-5869-46e2-9f60-2ef931b1c935" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_558cb4d7-c42c-4481-901f-c3c9017703bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_eef880e8-5869-46e2-9f60-2ef931b1c935" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_558cb4d7-c42c-4481-901f-c3c9017703bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_454af973-26fe-466e-ba60-f20c4f6ddf44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_eef880e8-5869-46e2-9f60-2ef931b1c935" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_454af973-26fe-466e-ba60-f20c4f6ddf44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_6367763c-ba73-4da2-8f92-060316a14519" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_6367763c-ba73-4da2-8f92-060316a14519" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_fcb8435b-19ee-4220-976f-1e88db528a47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_fcb8435b-19ee-4220-976f-1e88db528a47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_81f25bbe-2558-4891-9404-801d97bff521" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_81f25bbe-2558-4891-9404-801d97bff521" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DebtExtinguishmentSharesGivenUp_4cbe9659-90e6-4634-89f9-3057df9c3280" xlink:href="wdc-20250627.xsd#wdc_DebtExtinguishmentSharesGivenUp"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_wdc_DebtExtinguishmentSharesGivenUp_4cbe9659-90e6-4634-89f9-3057df9c3280" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_dc58c7c1-998f-4c40-9487-598936ad0e3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_dc58c7c1-998f-4c40-9487-598936ad0e3b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_95436a98-9a6c-4288-bc17-c5f09bf07c70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_95436a98-9a6c-4288-bc17-c5f09bf07c70" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_a6fd366c-1006-4428-bcb7-f51cd7364b55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_a6fd366c-1006-4428-bcb7-f51cd7364b55" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_cd437f45-0191-4ef7-a5c4-f336486d86e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_cd437f45-0191-4ef7-a5c4-f336486d86e2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_e8aebeb5-1c1a-4b27-8107-61a0188319e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_e8aebeb5-1c1a-4b27-8107-61a0188319e0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_28df0848-8f7a-401b-a716-bf121d80d4dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_28df0848-8f7a-401b-a716-bf121d80d4dd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f555c034-1f51-4bc0-b2a5-2a033e2afca8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f555c034-1f51-4bc0-b2a5-2a033e2afca8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_c0fbb1ac-94c8-4fec-8ce0-54add1a7cd6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_c0fbb1ac-94c8-4fec-8ce0-54add1a7cd6e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_6920cbd2-904b-4189-b5c8-00a39ffd257b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_6920cbd2-904b-4189-b5c8-00a39ffd257b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DebtInstrumentCovenantLeverageRatioMaximum_72de124e-315b-481c-9b6f-e1e405a29d2a" xlink:href="wdc-20250627.xsd#wdc_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_wdc_DebtInstrumentCovenantLeverageRatioMaximum_72de124e-315b-481c-9b6f-e1e405a29d2a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DebtInstrumentCovenantLeverageRatioMinimum_c6c5bd4c-49f2-4ded-a2e4-ee4364103634" xlink:href="wdc-20250627.xsd#wdc_DebtInstrumentCovenantLeverageRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_wdc_DebtInstrumentCovenantLeverageRatioMinimum_c6c5bd4c-49f2-4ded-a2e4-ee4364103634" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RedemptionOfSeniorDebt_c1c4ba93-d78d-49c4-8f96-96d129331a19" xlink:href="wdc-20250627.xsd#wdc_RedemptionOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_wdc_RedemptionOfSeniorDebt_c1c4ba93-d78d-49c4-8f96-96d129331a19" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_218be919-28b0-4dfb-a9be-43d1f364a29e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_218be919-28b0-4dfb-a9be-43d1f364a29e" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_551b771e-61cd-4055-9408-4765334f1306" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_551b771e-61cd-4055-9408-4765334f1306" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_e74a3f78-0dcc-40da-bb82-8a546c16e576" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_e74a3f78-0dcc-40da-bb82-8a546c16e576" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_0cc7687f-3cf7-4e26-a13b-d21c0cba9fbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_0cc7687f-3cf7-4e26-a13b-d21c0cba9fbe" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_fb246d3b-da0e-4e03-bc8d-a12fbd3b5718" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_fb246d3b-da0e-4e03-bc8d-a12fbd3b5718" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromConvertibleDebt_855c72c5-4aae-4e89-875a-7bc0320e61e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_ProceedsFromConvertibleDebt_855c72c5-4aae-4e89-875a-7bc0320e61e9" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativePriceRiskOptionStrikePrice_817be939-d201-485c-85d0-781a779969ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativePriceRiskOptionStrikePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DerivativePriceRiskOptionStrikePrice_817be939-d201-485c-85d0-781a779969ef" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCapPrice_57513d71-7f06-4d0e-b9c5-ce2b761cc5c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCapPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DerivativeCapPrice_57513d71-7f06-4d0e-b9c5-ce2b761cc5c5" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_534b362a-b8da-4344-9c2c-812e6380b542" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_534b362a-b8da-4344-9c2c-812e6380b542" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_fcc9d017-52b8-4e0f-b90c-ffe2db32914f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_fcc9d017-52b8-4e0f-b90c-ffe2db32914f" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchaseAmount_544016bf-cec1-40d3-9468-d7bae8940616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRepurchaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_DebtInstrumentRepurchaseAmount_544016bf-cec1-40d3-9468-d7bae8940616" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfConvertibleDebt_a2fc955e-9e01-4f4f-9234-8fa0473e27a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_c3ab3ac1-ac16-4097-b275-a8ee7d87da22" xlink:to="loc_us-gaap_RepaymentsOfConvertibleDebt_a2fc955e-9e01-4f4f-9234-8fa0473e27a1" xlink:type="arc" order="27"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/PensionandOtherPostRetirementBenefitPlansAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#PensionandOtherPostRetirementBenefitPlansAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/PensionandOtherPostRetirementBenefitPlansAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d07dd9e7-f196-434e-a9d2-c4f3154850d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d07dd9e7-f196-434e-a9d2-c4f3154850d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_e9a9ee17-650c-472d-a739-274ee0f7f247" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_d07dd9e7-f196-434e-a9d2-c4f3154850d0" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_e9a9ee17-650c-472d-a739-274ee0f7f247" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_e9a9ee17-650c-472d-a739-274ee0f7f247_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_e9a9ee17-650c-472d-a739-274ee0f7f247" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_e9a9ee17-650c-472d-a739-274ee0f7f247_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_0ff9d800-cf34-4158-b14b-1b3d16efac2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_e9a9ee17-650c-472d-a739-274ee0f7f247" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_0ff9d800-cf34-4158-b14b-1b3d16efac2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_0b8aa43f-9fc3-4272-83f0-9aae53103eb8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDebtSecurityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_0ff9d800-cf34-4158-b14b-1b3d16efac2e" xlink:to="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_0b8aa43f-9fc3-4272-83f0-9aae53103eb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_4fa8ae11-8696-4553-ad53-e2d5054d6eac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_0ff9d800-cf34-4158-b14b-1b3d16efac2e" xlink:to="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_4fa8ae11-8696-4553-ad53-e2d5054d6eac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DefinedBenefitPlanOtherAssetsMember_c95f9e1e-3bfa-4cb8-b3ca-44544d041d60" xlink:href="wdc-20250627.xsd#wdc_DefinedBenefitPlanOtherAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_0ff9d800-cf34-4158-b14b-1b3d16efac2e" xlink:to="loc_wdc_DefinedBenefitPlanOtherAssetsMember_c95f9e1e-3bfa-4cb8-b3ca-44544d041d60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_93ff7842-0c99-4d82-9072-d181e1231d69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_93ff7842-0c99-4d82-9072-d181e1231d69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_e5e00994-513e-48d4-beb5-2089a0a387ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_e5e00994-513e-48d4-beb5-2089a0a387ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_ec7f8bf2-b5cf-4fe9-8d3a-69af2069cfdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_ec7f8bf2-b5cf-4fe9-8d3a-69af2069cfdd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PriorServiceCreditsForDefinedBenefitPensionPlansIncludedInAccumulatedOtherComprehensiveIncomeAtBalanceSheetDate_ee254f03-f51b-4b1a-8bf8-caf0b18b5010" xlink:href="wdc-20250627.xsd#wdc_PriorServiceCreditsForDefinedBenefitPensionPlansIncludedInAccumulatedOtherComprehensiveIncomeAtBalanceSheetDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_wdc_PriorServiceCreditsForDefinedBenefitPensionPlansIncludedInAccumulatedOtherComprehensiveIncomeAtBalanceSheetDate_ee254f03-f51b-4b1a-8bf8-caf0b18b5010" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_4b16d380-2a11-4729-ac12-95cc2e73e5a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_4b16d380-2a11-4729-ac12-95cc2e73e5a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DefinedBenefitPlanEstimatedAnnualBenefitsPaymentPeriod_d38062e6-3329-4527-96e0-876113be2812" xlink:href="wdc-20250627.xsd#wdc_DefinedBenefitPlanEstimatedAnnualBenefitsPaymentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_488b91a8-ecb0-4a2a-b0c9-35bd46b9cf1f" xlink:to="loc_wdc_DefinedBenefitPlanEstimatedAnnualBenefitsPaymentPeriod_d38062e6-3329-4527-96e0-876113be2812" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/PensionandOtherPostRetirementBenefitPlansDefinedBenefitPensionPlansMajorAssetCategoriesandTheirAssociatedFairValuesDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#PensionandOtherPostRetirementBenefitPlansDefinedBenefitPensionPlansMajorAssetCategoriesandTheirAssociatedFairValuesDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/PensionandOtherPostRetirementBenefitPlansDefinedBenefitPensionPlansMajorAssetCategoriesandTheirAssociatedFairValuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03bb7bff-ad7f-4400-b1c9-80af1860c0cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_dee0b65d-b6e6-4e44-9073-b3b308e91089" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03bb7bff-ad7f-4400-b1c9-80af1860c0cd" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_dee0b65d-b6e6-4e44-9073-b3b308e91089" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_652f6724-6dea-489e-ac40-fa2e65faf07e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_dee0b65d-b6e6-4e44-9073-b3b308e91089" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_652f6724-6dea-489e-ac40-fa2e65faf07e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_652f6724-6dea-489e-ac40-fa2e65faf07e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_652f6724-6dea-489e-ac40-fa2e65faf07e" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_652f6724-6dea-489e-ac40-fa2e65faf07e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_652f6724-6dea-489e-ac40-fa2e65faf07e" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DefinedBenefitPlanEquityCommingledMutualFundsMember_d27cdad5-aa70-4bbc-84b2-f0d081d6a108" xlink:href="wdc-20250627.xsd#wdc_DefinedBenefitPlanEquityCommingledMutualFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:to="loc_wdc_DefinedBenefitPlanEquityCommingledMutualFundsMember_d27cdad5-aa70-4bbc-84b2-f0d081d6a108" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DefinedBenefitPlanFixedIncomeCommingledMutualFundsMember_037255a3-61f9-40c4-ab31-3cdd344fc6e9" xlink:href="wdc-20250627.xsd#wdc_DefinedBenefitPlanFixedIncomeCommingledMutualFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:to="loc_wdc_DefinedBenefitPlanFixedIncomeCommingledMutualFundsMember_037255a3-61f9-40c4-ab31-3cdd344fc6e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_NetPlanAssetsSubjectToLevelingMember_17e06507-d0a0-432b-8c0d-f3e4a13f82f7" xlink:href="wdc-20250627.xsd#wdc_NetPlanAssetsSubjectToLevelingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:to="loc_wdc_NetPlanAssetsSubjectToLevelingMember_17e06507-d0a0-432b-8c0d-f3e4a13f82f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RealEstateInvestmentTrustMember_953ce5e3-73f3-4edf-864d-0f76b4ac4eb0" xlink:href="wdc-20250627.xsd#wdc_RealEstateInvestmentTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:to="loc_wdc_RealEstateInvestmentTrustMember_953ce5e3-73f3-4edf-864d-0f76b4ac4eb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TotalInvestmentsAtFairValueMember_f90bb0dc-ff26-4d99-83c9-3c79424a7e34" xlink:href="wdc-20250627.xsd#wdc_TotalInvestmentsAtFairValueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_88788cdb-46b4-40f2-80ac-dd3c2b2aa46c" xlink:to="loc_wdc_TotalInvestmentsAtFairValueMember_f90bb0dc-ff26-4d99-83c9-3c79424a7e34" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1cc4e5e1-fc72-4fde-8d52-cfb34095f696" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_dee0b65d-b6e6-4e44-9073-b3b308e91089" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1cc4e5e1-fc72-4fde-8d52-cfb34095f696" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1cc4e5e1-fc72-4fde-8d52-cfb34095f696_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1cc4e5e1-fc72-4fde-8d52-cfb34095f696" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1cc4e5e1-fc72-4fde-8d52-cfb34095f696_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_58b9f68f-ea04-4169-8845-a6494bd6f189" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1cc4e5e1-fc72-4fde-8d52-cfb34095f696" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_58b9f68f-ea04-4169-8845-a6494bd6f189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel12And3Member_ba365b65-3ee2-4838-bd41-8b7377750ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel12And3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_58b9f68f-ea04-4169-8845-a6494bd6f189" xlink:to="loc_us-gaap_FairValueInputsLevel12And3Member_ba365b65-3ee2-4838-bd41-8b7377750ab5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1956f104-d99d-4d3e-b54b-9a614f512563" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_ba365b65-3ee2-4838-bd41-8b7377750ab5" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1956f104-d99d-4d3e-b54b-9a614f512563" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_ead7c42b-f34e-4984-b79b-cb1f629b520a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_ba365b65-3ee2-4838-bd41-8b7377750ab5" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_ead7c42b-f34e-4984-b79b-cb1f629b520a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_b74f05bd-aea2-45e6-a870-893215be5ee0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_ba365b65-3ee2-4838-bd41-8b7377750ab5" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_b74f05bd-aea2-45e6-a870-893215be5ee0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_fa59c6f4-8b7f-4104-8a4a-f7274c875442" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_58b9f68f-ea04-4169-8845-a6494bd6f189" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_fa59c6f4-8b7f-4104-8a4a-f7274c875442" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsInvestmentWithinPlanAssetCategoryAmount_6c78eb40-7883-4fef-831b-1827e8016266" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsInvestmentWithinPlanAssetCategoryAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03bb7bff-ad7f-4400-b1c9-80af1860c0cd" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsInvestmentWithinPlanAssetCategoryAmount_6c78eb40-7883-4fef-831b-1827e8016266" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/WesternDigitalCorporation401kPlanAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#WesternDigitalCorporation401kPlanAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/WesternDigitalCorporation401kPlanAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e97ea144-f561-4596-a91c-c30200f9fb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e97ea144-f561-4596-a91c-c30200f9fb5c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxScenarioAxis_5e36bb9d-126b-4973-906a-36fa539dc46f" xlink:href="wdc-20250627.xsd#wdc_TaxScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e97ea144-f561-4596-a91c-c30200f9fb5c" xlink:to="loc_wdc_TaxScenarioAxis_5e36bb9d-126b-4973-906a-36fa539dc46f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxScenarioDomain_5e36bb9d-126b-4973-906a-36fa539dc46f_default" xlink:href="wdc-20250627.xsd#wdc_TaxScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_wdc_TaxScenarioAxis_5e36bb9d-126b-4973-906a-36fa539dc46f" xlink:to="loc_wdc_TaxScenarioDomain_5e36bb9d-126b-4973-906a-36fa539dc46f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxScenarioDomain_17d7dbb2-8523-48d4-b840-ef63a9fb3c1c" xlink:href="wdc-20250627.xsd#wdc_TaxScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_wdc_TaxScenarioAxis_5e36bb9d-126b-4973-906a-36fa539dc46f" xlink:to="loc_wdc_TaxScenarioDomain_17d7dbb2-8523-48d4-b840-ef63a9fb3c1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PreTaxMember_68957472-c227-4cf5-8352-a804109ad2a2" xlink:href="wdc-20250627.xsd#wdc_PreTaxMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_TaxScenarioDomain_17d7dbb2-8523-48d4-b840-ef63a9fb3c1c" xlink:to="loc_wdc_PreTaxMember_68957472-c227-4cf5-8352-a804109ad2a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PreTaxCatchUpMember_8c39a7a6-4c69-468e-9996-c48d7332fc5a" xlink:href="wdc-20250627.xsd#wdc_PreTaxCatchUpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_TaxScenarioDomain_17d7dbb2-8523-48d4-b840-ef63a9fb3c1c" xlink:to="loc_wdc_PreTaxCatchUpMember_8c39a7a6-4c69-468e-9996-c48d7332fc5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_5aacb09e-a3ad-4f10-ad18-c99a36139896" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:to="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_5aacb09e-a3ad-4f10-ad18-c99a36139896" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_430d9880-96a9-4bd9-8046-887a125cd370" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_430d9880-96a9-4bd9-8046-887a125cd370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_fb5d4dcb-7350-4b43-91bb-a3d3f7d1d46a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_fb5d4dcb-7350-4b43-91bb-a3d3f7d1d46a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_0c2a4b52-2df3-4527-aa55-6fc550311ed4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_f666b056-d753-4709-97ff-c3bc8f4122a2" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_0c2a4b52-2df3-4527-aa55-6fc550311ed4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockNarrativeDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a88bb591-ce2e-4cb6-a703-18624c4ef298" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:to="loc_srt_RangeAxis_a88bb591-ce2e-4cb6-a703-18624c4ef298" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a88bb591-ce2e-4cb6-a703-18624c4ef298_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a88bb591-ce2e-4cb6-a703-18624c4ef298" xlink:to="loc_srt_RangeMember_a88bb591-ce2e-4cb6-a703-18624c4ef298_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_58de1d26-65b9-4fa2-8b62-e5433661d443" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a88bb591-ce2e-4cb6-a703-18624c4ef298" xlink:to="loc_srt_RangeMember_58de1d26-65b9-4fa2-8b62-e5433661d443" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d4df2026-b3ab-4d6d-95d6-e7110ddd4a79" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_58de1d26-65b9-4fa2-8b62-e5433661d443" xlink:to="loc_srt_MinimumMember_d4df2026-b3ab-4d6d-95d6-e7110ddd4a79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_12587698-f06b-4851-a673-02d99c3bd7c0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_58de1d26-65b9-4fa2-8b62-e5433661d443" xlink:to="loc_srt_MaximumMember_12587698-f06b-4851-a673-02d99c3bd7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0e692744-eee3-49e9-b224-a664261e414a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:to="loc_us-gaap_AwardTypeAxis_0e692744-eee3-49e9-b224-a664261e414a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0e692744-eee3-49e9-b224-a664261e414a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0e692744-eee3-49e9-b224-a664261e414a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0e692744-eee3-49e9-b224-a664261e414a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b13a298-97f8-4af2-ac85-0b3380462462" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0e692744-eee3-49e9-b224-a664261e414a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b13a298-97f8-4af2-ac85-0b3380462462" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_37b25710-703a-467a-b9d9-e1a06474e840" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b13a298-97f8-4af2-ac85-0b3380462462" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_37b25710-703a-467a-b9d9-e1a06474e840" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_76b27108-bdf2-4dc0-b284-f9a984deaf0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b13a298-97f8-4af2-ac85-0b3380462462" xlink:to="loc_us-gaap_EmployeeStockMember_76b27108-bdf2-4dc0-b284-f9a984deaf0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_OutstandingAwardsAndSharesAvailableForAwardMember_ee7ac150-55d2-4e64-b10b-264c08d2beb1" xlink:href="wdc-20250627.xsd#wdc_OutstandingAwardsAndSharesAvailableForAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b13a298-97f8-4af2-ac85-0b3380462462" xlink:to="loc_wdc_OutstandingAwardsAndSharesAvailableForAwardMember_ee7ac150-55d2-4e64-b10b-264c08d2beb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_ae4b0007-fe00-4d02-8c8a-55e818a07453" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:to="loc_us-gaap_PlanNameAxis_ae4b0007-fe00-4d02-8c8a-55e818a07453" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_ae4b0007-fe00-4d02-8c8a-55e818a07453_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_ae4b0007-fe00-4d02-8c8a-55e818a07453" xlink:to="loc_us-gaap_PlanNameDomain_ae4b0007-fe00-4d02-8c8a-55e818a07453_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_abe4e45c-e17b-49f3-b38e-2274b7f0d012" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_ae4b0007-fe00-4d02-8c8a-55e818a07453" xlink:to="loc_us-gaap_PlanNameDomain_abe4e45c-e17b-49f3-b38e-2274b7f0d012" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_A2021LongTermIncentivePlanMember_f2589d0e-02cb-4064-a03e-d55e1d1775cf" xlink:href="wdc-20250627.xsd#wdc_A2021LongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_abe4e45c-e17b-49f3-b38e-2274b7f0d012" xlink:to="loc_wdc_A2021LongTermIncentivePlanMember_f2589d0e-02cb-4064-a03e-d55e1d1775cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_b2e7da51-1e9e-4978-97d4-187ec50d2e00" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9002b936-fb49-449b-9454-5ec3b0d59122" xlink:to="loc_dei_LegalEntityAxis_b2e7da51-1e9e-4978-97d4-187ec50d2e00" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_b2e7da51-1e9e-4978-97d4-187ec50d2e00_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_b2e7da51-1e9e-4978-97d4-187ec50d2e00" xlink:to="loc_dei_EntityDomain_b2e7da51-1e9e-4978-97d4-187ec50d2e00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_23d4bcd9-f806-4f36-ba1d-d5d9c0947a0f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_b2e7da51-1e9e-4978-97d4-187ec50d2e00" xlink:to="loc_dei_EntityDomain_23d4bcd9-f806-4f36-ba1d-d5d9c0947a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SanDiskMember_85a4713a-332e-43a5-a2cd-6ce568530e85" xlink:href="wdc-20250627.xsd#wdc_SanDiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_23d4bcd9-f806-4f36-ba1d-d5d9c0947a0f" xlink:to="loc_wdc_SanDiskMember_85a4713a-332e-43a5-a2cd-6ce568530e85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_0057b39f-44dc-49d0-9db8-57c02045c12f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_0057b39f-44dc-49d0-9db8-57c02045c12f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_52630da1-b8fd-4c40-b875-5ae48cac8e25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_52630da1-b8fd-4c40-b875-5ae48cac8e25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_a87a445a-3759-4965-962f-b24ed6f34c29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_a87a445a-3759-4965-962f-b24ed6f34c29" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_ca61c9f1-09ce-49ab-ae58-fc3ef6ce105b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_ca61c9f1-09ce-49ab-ae58-fc3ef6ce105b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_5c7de170-7d6a-4f21-84ff-e16ff9c624b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_5c7de170-7d6a-4f21-84ff-e16ff9c624b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfOfferingPeriods_5a06e7c8-fe33-4587-aea4-b28275fe126c" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfOfferingPeriods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfOfferingPeriods_5a06e7c8-fe33-4587-aea4-b28275fe126c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardConsecutiveOfferingPeriod_f8af807d-c12d-471f-a99c-2df57f8bf8c2" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardConsecutiveOfferingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardConsecutiveOfferingPeriod_f8af807d-c12d-471f-a99c-2df57f8bf8c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPurchasePeriods_954ed5c4-146a-475b-92a5-531475c7de72" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPurchasePeriods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPurchasePeriods_954ed5c4-146a-475b-92a5-531475c7de72" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod_1d2fa342-151a-4567-8622-53da14082895" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod_1d2fa342-151a-4567-8622-53da14082895" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_3139c2c7-bab6-408d-b62a-4afc0a3335a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_3139c2c7-bab6-408d-b62a-4afc0a3335a4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_f2700836-454f-44f6-8df4-37e01ac18536" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_f2700836-454f-44f6-8df4-37e01ac18536" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardAverageClosingPriceTradingDays_e1b3129d-1daa-4246-9c28-897831933941" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardAverageClosingPriceTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardAverageClosingPriceTradingDays_e1b3129d-1daa-4246-9c28-897831933941" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncrementalValueAdjustmentOfUnvestedAwards_898aafeb-17bc-47fc-b82f-52849c4b7b5b" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncrementalValueAdjustmentOfUnvestedAwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncrementalValueAdjustmentOfUnvestedAwards_898aafeb-17bc-47fc-b82f-52849c4b7b5b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesUnvested_d8ba14b1-a152-48c7-a28a-924b5fda1d7a" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesUnvested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesUnvested_d8ba14b1-a152-48c7-a28a-924b5fda1d7a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_fe30a840-03c3-4dd8-a44a-80b748f87cf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_fe30a840-03c3-4dd8-a44a-80b748f87cf0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_eeb9f37b-2cb4-4575-be2b-bb3901c0d407" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_35a835e8-efe8-48ed-8f9f-baac8137a9a2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_eeb9f37b-2cb4-4575-be2b-bb3901c0d407" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0a185a6-c376-4995-a50c-a5a6a83404f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ff65ae67-579e-424b-a7d7-6c5420b0564c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0a185a6-c376-4995-a50c-a5a6a83404f0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ff65ae67-579e-424b-a7d7-6c5420b0564c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_78b3cb6e-e74e-4a91-b40f-85379d02f577" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ff65ae67-579e-424b-a7d7-6c5420b0564c" xlink:to="loc_us-gaap_AwardTypeAxis_78b3cb6e-e74e-4a91-b40f-85379d02f577" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78b3cb6e-e74e-4a91-b40f-85379d02f577_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_78b3cb6e-e74e-4a91-b40f-85379d02f577" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78b3cb6e-e74e-4a91-b40f-85379d02f577_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_90986465-bb61-4d86-9ce4-ddcd3aa8f1e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_78b3cb6e-e74e-4a91-b40f-85379d02f577" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_90986465-bb61-4d86-9ce4-ddcd3aa8f1e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_e5af5b03-65b9-428f-8bfb-35b85f3d24d8" xlink:href="wdc-20250627.xsd#wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_90986465-bb61-4d86-9ce4-ddcd3aa8f1e1" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_e5af5b03-65b9-428f-8bfb-35b85f3d24d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_00827d3b-3334-4183-bf16-88c4e1a00e4d" xlink:href="wdc-20250627.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_90986465-bb61-4d86-9ce4-ddcd3aa8f1e1" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_00827d3b-3334-4183-bf16-88c4e1a00e4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_131d701f-949c-4c6f-96a4-2f8959e80519" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ff65ae67-579e-424b-a7d7-6c5420b0564c" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_131d701f-949c-4c6f-96a4-2f8959e80519" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_131d701f-949c-4c6f-96a4-2f8959e80519_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_131d701f-949c-4c6f-96a4-2f8959e80519" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_131d701f-949c-4c6f-96a4-2f8959e80519_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_649148a6-5215-41ee-8d1a-327d9671a5db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_131d701f-949c-4c6f-96a4-2f8959e80519" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_649148a6-5215-41ee-8d1a-327d9671a5db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_f86bfc1d-70f7-4f8f-8747-f3130aeb6aaf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_649148a6-5215-41ee-8d1a-327d9671a5db" xlink:to="loc_us-gaap_CostOfSalesMember_f86bfc1d-70f7-4f8f-8747-f3130aeb6aaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_b6efd268-9bb9-4f65-8522-edb781cb191a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_649148a6-5215-41ee-8d1a-327d9671a5db" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_b6efd268-9bb9-4f65-8522-edb781cb191a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_30b9a1f0-740b-47c6-8a57-f80a7735e3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_649148a6-5215-41ee-8d1a-327d9671a5db" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_30b9a1f0-740b-47c6-8a57-f80a7735e3ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_98fe7eda-7bc0-40a6-a13d-2b3b7fd25085" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0a185a6-c376-4995-a50c-a5a6a83404f0" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_98fe7eda-7bc0-40a6-a13d-2b3b7fd25085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_eb0bd456-4fcd-4d96-8b26-4b214c31e16a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0a185a6-c376-4995-a50c-a5a6a83404f0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_eb0bd456-4fcd-4d96-8b26-4b214c31e16a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_3f09fdd1-5ffa-47f5-ab07-37740106d1ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0a185a6-c376-4995-a50c-a5a6a83404f0" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_3f09fdd1-5ffa-47f5-ab07-37740106d1ee" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockUnrecognizedSharebasedCompensationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockUnrecognizedSharebasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockUnrecognizedSharebasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsLineItems_13d4b70f-97ae-4205-b80d-ed5848f39646" xlink:href="wdc-20250627.xsd#wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsTable_e843d833-6660-4b39-b019-d57a0fea676f" xlink:href="wdc-20250627.xsd#wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsLineItems_13d4b70f-97ae-4205-b80d-ed5848f39646" xlink:to="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsTable_e843d833-6660-4b39-b019-d57a0fea676f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_34f2dfd3-5ab6-4a68-a585-d705b67bc802" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsTable_e843d833-6660-4b39-b019-d57a0fea676f" xlink:to="loc_us-gaap_AwardTypeAxis_34f2dfd3-5ab6-4a68-a585-d705b67bc802" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_34f2dfd3-5ab6-4a68-a585-d705b67bc802_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_34f2dfd3-5ab6-4a68-a585-d705b67bc802" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_34f2dfd3-5ab6-4a68-a585-d705b67bc802_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83b9897e-ee4d-4919-8ce6-56cf38cac46c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_34f2dfd3-5ab6-4a68-a585-d705b67bc802" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83b9897e-ee4d-4919-8ce6-56cf38cac46c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_a3233129-cd8e-4d70-a616-2c06df237468" xlink:href="wdc-20250627.xsd#wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83b9897e-ee4d-4919-8ce6-56cf38cac46c" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_a3233129-cd8e-4d70-a616-2c06df237468" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_527cccef-dd54-48a8-ad91-7344de5d2134" xlink:href="wdc-20250627.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_83b9897e-ee4d-4919-8ce6-56cf38cac46c" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_527cccef-dd54-48a8-ad91-7344de5d2134" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_7f0f0b77-ad5e-4a98-ae3e-3e695d04a564" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsLineItems_13d4b70f-97ae-4205-b80d-ed5848f39646" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_7f0f0b77-ad5e-4a98-ae3e-3e695d04a564" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b02058ff-926a-485d-815e-7bfe5ada502c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_EmployeeServiceSharebasedCompensationUnrecognizedServiceCostsLineItems_13d4b70f-97ae-4205-b80d-ed5848f39646" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b02058ff-926a-485d-815e-7bfe5ada502c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockRestrictedStockUnitsAndPerformanceShareUnitsDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockRestrictedStockUnitsAndPerformanceShareUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockRestrictedStockUnitsAndPerformanceShareUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2bbbe0f2-187f-4a02-90e2-2fea509ffadc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7de9e285-5b15-48eb-a638-d2101a41996a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2bbbe0f2-187f-4a02-90e2-2fea509ffadc" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7de9e285-5b15-48eb-a638-d2101a41996a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_9333bd31-07a6-4a7a-8c02-a5ad19f17262" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7de9e285-5b15-48eb-a638-d2101a41996a" xlink:to="loc_us-gaap_AwardTypeAxis_9333bd31-07a6-4a7a-8c02-a5ad19f17262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9333bd31-07a6-4a7a-8c02-a5ad19f17262_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9333bd31-07a6-4a7a-8c02-a5ad19f17262" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9333bd31-07a6-4a7a-8c02-a5ad19f17262_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fbe60cc-2084-43f3-9223-505947b01f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9333bd31-07a6-4a7a-8c02-a5ad19f17262" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fbe60cc-2084-43f3-9223-505947b01f6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember_775bbaff-d2c7-47d0-9faf-06c18584fe7a" xlink:href="wdc-20250627.xsd#wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fbe60cc-2084-43f3-9223-505947b01f6c" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember_775bbaff-d2c7-47d0-9faf-06c18584fe7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2bbbe0f2-187f-4a02-90e2-2fea509ffadc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a1554739-ebef-43e6-8e75-5bf284e7fa65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a1554739-ebef-43e6-8e75-5bf284e7fa65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0e65ad81-d040-416a-87f3-3b4c48c06bef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0e65ad81-d040-416a-87f3-3b4c48c06bef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a61670ff-67f4-45b9-a5f7-d3765ee38365" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a61670ff-67f4-45b9-a5f7-d3765ee38365" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1bd51d2b-bd97-4adc-ba1f-683817363f7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1bd51d2b-bd97-4adc-ba1f-683817363f7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparation_21f17709-5941-44bb-9b21-08e38eb8326a" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparation_21f17709-5941-44bb-9b21-08e38eb8326a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparation_785382e1-2685-4606-9d55-bd4c83c81487" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_c47c2508-3ca6-4ed0-b867-735af996f038" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparation_785382e1-2685-4606-9d55-bd4c83c81487" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d094c5c6-66c6-4caa-8df8-29cbf2d1f0bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2bbbe0f2-187f-4a02-90e2-2fea509ffadc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7e226eb3-f5b4-4d60-9d84-2358ecf50ba2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7e226eb3-f5b4-4d60-9d84-2358ecf50ba2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6a73b67b-fdfc-4f01-a6fe-172e5bf9a29f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_6a73b67b-fdfc-4f01-a6fe-172e5bf9a29f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a9e34c6b-a9c9-431e-aa3c-675b0315ef2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a9e34c6b-a9c9-431e-aa3c-675b0315ef2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue_87e86da9-ef8f-4f61-8d52-0f2ccee99ba2" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue_87e86da9-ef8f-4f61-8d52-0f2ccee99ba2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparationWeightedAverageGrantDateFairValue_077b1481-3986-44d2-b2c4-857a2b8de249" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparationWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareModificationDueToSeparationWeightedAverageGrantDateFairValue_077b1481-3986-44d2-b2c4-857a2b8de249" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparationWeightedAverageGrantDateFairValue_45c10632-e117-4ea6-9e07-db71a4f638c4" xlink:href="wdc-20250627.xsd#wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparationWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0763f5be-c0ec-4e74-babf-9f181adf0fa3" xlink:to="loc_wdc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardsCancelledDueToSeparationWeightedAverageGrantDateFairValue_45c10632-e117-4ea6-9e07-db71a4f638c4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_29f7784d-a9cb-499c-920a-33525371e233" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_AggregateValueOfRestrictedStockAwardsVested_12ed78f0-a568-467f-87d5-dc3bc8c3341a" xlink:href="wdc-20250627.xsd#wdc_AggregateValueOfRestrictedStockAwardsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2bbbe0f2-187f-4a02-90e2-2fea509ffadc" xlink:to="loc_wdc_AggregateValueOfRestrictedStockAwardsVested_12ed78f0-a568-467f-87d5-dc3bc8c3341a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockFairValuesAssumptionsUserForEmployeeStockPurchasePlanGrantedDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockFairValuesAssumptionsUserForEmployeeStockPurchasePlanGrantedDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockFairValuesAssumptionsUserForEmployeeStockPurchasePlanGrantedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbca104c-dadc-46d6-9614-451cfd1381cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbca104c-dadc-46d6-9614-451cfd1381cc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_f0e9dd0c-c472-43a7-8917-8538c8a95a69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbca104c-dadc-46d6-9614-451cfd1381cc" xlink:to="loc_us-gaap_AwardTypeAxis_f0e9dd0c-c472-43a7-8917-8538c8a95a69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0e9dd0c-c472-43a7-8917-8538c8a95a69_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_f0e9dd0c-c472-43a7-8917-8538c8a95a69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f0e9dd0c-c472-43a7-8917-8538c8a95a69_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cb8c1600-6df6-4938-b32f-04decab1c38e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_f0e9dd0c-c472-43a7-8917-8538c8a95a69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cb8c1600-6df6-4938-b32f-04decab1c38e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_003cca05-de7b-4143-aa37-b50e3a15df26" xlink:href="wdc-20250627.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cb8c1600-6df6-4938-b32f-04decab1c38e" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_003cca05-de7b-4143-aa37-b50e3a15df26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_d3cc77a2-3d5f-4bc0-9896-b87e0ce4e8ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_d3cc77a2-3d5f-4bc0-9896-b87e0ce4e8ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8a0252b8-66ef-4ccb-9f8a-2a8282dd51d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8a0252b8-66ef-4ccb-9f8a-2a8282dd51d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e60134d0-3ca0-44d0-8756-7ae33752030a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e60134d0-3ca0-44d0-8756-7ae33752030a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_6f2ecb77-6b2b-4e4a-9b96-0e30a6a76bb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_6f2ecb77-6b2b-4e4a-9b96-0e30a6a76bb4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2b188e57-d596-4b89-811f-2d47b1c8397f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fe11399c-2166-4c46-b049-91cd6136a0b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2b188e57-d596-4b89-811f-2d47b1c8397f" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockShareRepurchaseProgramandDividendsDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockShareRepurchaseProgramandDividendsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockShareRepurchaseProgramandDividendsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0011fba8-e0a1-466b-805c-1760df3546fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0011fba8-e0a1-466b-805c-1760df3546fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0011fba8-e0a1-466b-805c-1760df3546fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0011fba8-e0a1-466b-805c-1760df3546fc" xlink:to="loc_us-gaap_ClassOfStockDomain_0011fba8-e0a1-466b-805c-1760df3546fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_dc03673d-7a85-4e33-b2a5-bc7d287cb8fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0011fba8-e0a1-466b-805c-1760df3546fc" xlink:to="loc_us-gaap_ClassOfStockDomain_dc03673d-7a85-4e33-b2a5-bc7d287cb8fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_ede63ca7-3d36-497d-88f3-c61d2d355e82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_dc03673d-7a85-4e33-b2a5-bc7d287cb8fa" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_ede63ca7-3d36-497d-88f3-c61d2d355e82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_fad60302-b025-4778-9c8a-9bb2e6dff5c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_dc03673d-7a85-4e33-b2a5-bc7d287cb8fa" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_fad60302-b025-4778-9c8a-9bb2e6dff5c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_4f590bd8-2997-4b48-8a2f-20bd360c0922" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_4f590bd8-2997-4b48-8a2f-20bd360c0922" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_4f590bd8-2997-4b48-8a2f-20bd360c0922_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_4f590bd8-2997-4b48-8a2f-20bd360c0922" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_4f590bd8-2997-4b48-8a2f-20bd360c0922_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_fb75b53c-163d-4723-8445-fa4d8a91c80e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_4f590bd8-2997-4b48-8a2f-20bd360c0922" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_fb75b53c-163d-4723-8445-fa4d8a91c80e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_0d4a85c4-81f3-4b5a-b5d0-02de22ba5e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_fb75b53c-163d-4723-8445-fa4d8a91c80e" xlink:to="loc_us-gaap_PrivatePlacementMember_0d4a85c4-81f3-4b5a-b5d0-02de22ba5e4f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_856eef9e-3159-4c5c-9d2c-10cc162a3e74" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_srt_RangeAxis_856eef9e-3159-4c5c-9d2c-10cc162a3e74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_856eef9e-3159-4c5c-9d2c-10cc162a3e74_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_856eef9e-3159-4c5c-9d2c-10cc162a3e74" xlink:to="loc_srt_RangeMember_856eef9e-3159-4c5c-9d2c-10cc162a3e74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8d95d9af-066b-453c-92a4-6172db6b8f60" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_856eef9e-3159-4c5c-9d2c-10cc162a3e74" xlink:to="loc_srt_RangeMember_8d95d9af-066b-453c-92a4-6172db6b8f60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4ad9a13b-750a-4e80-8997-94160484f787" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8d95d9af-066b-453c-92a4-6172db6b8f60" xlink:to="loc_srt_MaximumMember_4ad9a13b-750a-4e80-8997-94160484f787" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_99e9513e-6391-4e91-b53e-b8b13b9030b8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8d95d9af-066b-453c-92a4-6172db6b8f60" xlink:to="loc_srt_MinimumMember_99e9513e-6391-4e91-b53e-b8b13b9030b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DividendRateDateAxis_d05e3358-1718-4c0a-89ab-2a36743a452d" xlink:href="wdc-20250627.xsd#wdc_DividendRateDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_wdc_DividendRateDateAxis_d05e3358-1718-4c0a-89ab-2a36743a452d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DividendRateDateDomain_d05e3358-1718-4c0a-89ab-2a36743a452d_default" xlink:href="wdc-20250627.xsd#wdc_DividendRateDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_wdc_DividendRateDateAxis_d05e3358-1718-4c0a-89ab-2a36743a452d" xlink:to="loc_wdc_DividendRateDateDomain_d05e3358-1718-4c0a-89ab-2a36743a452d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DividendRateDateDomain_2e4bf4ab-fea7-46ba-8349-f36a8c8e4d84" xlink:href="wdc-20250627.xsd#wdc_DividendRateDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_wdc_DividendRateDateAxis_d05e3358-1718-4c0a-89ab-2a36743a452d" xlink:to="loc_wdc_DividendRateDateDomain_2e4bf4ab-fea7-46ba-8349-f36a8c8e4d84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_January312030Member_703f426a-2085-4c10-b15c-07a7a5138957" xlink:href="wdc-20250627.xsd#wdc_January312030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_DividendRateDateDomain_2e4bf4ab-fea7-46ba-8349-f36a8c8e4d84" xlink:to="loc_wdc_January312030Member_703f426a-2085-4c10-b15c-07a7a5138957" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_January312033Member_9cc819b1-23b0-4431-a9cb-02d491d66fc2" xlink:href="wdc-20250627.xsd#wdc_January312033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_DividendRateDateDomain_2e4bf4ab-fea7-46ba-8349-f36a8c8e4d84" xlink:to="loc_wdc_January312033Member_9cc819b1-23b0-4431-a9cb-02d491d66fc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_aa28718d-9a93-465a-85b3-3add742a24ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_aa28718d-9a93-465a-85b3-3add742a24ef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_aa28718d-9a93-465a-85b3-3add742a24ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_aa28718d-9a93-465a-85b3-3add742a24ef" xlink:to="loc_us-gaap_EquityComponentDomain_aa28718d-9a93-465a-85b3-3add742a24ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_59664613-4799-43c0-bc13-5ffe4ce51d52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_aa28718d-9a93-465a-85b3-3add742a24ef" xlink:to="loc_us-gaap_EquityComponentDomain_59664613-4799-43c0-bc13-5ffe4ce51d52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_df14549f-e65c-43b4-846c-86b772ff389d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_59664613-4799-43c0-bc13-5ffe4ce51d52" xlink:to="loc_us-gaap_CommonStockMember_df14549f-e65c-43b4-846c-86b772ff389d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_cec4c4d7-f5a6-4923-be36-3095661194ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62e5a5e3-baa7-4d63-8e75-79613143e1d6" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_cec4c4d7-f5a6-4923-be36-3095661194ea" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_cec4c4d7-f5a6-4923-be36-3095661194ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_cec4c4d7-f5a6-4923-be36-3095661194ea" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_cec4c4d7-f5a6-4923-be36-3095661194ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_bad93eee-2f15-4b1f-ad00-4394248ac1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_cec4c4d7-f5a6-4923-be36-3095661194ea" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_bad93eee-2f15-4b1f-ad00-4394248ac1ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_ed6bfa10-30fe-4acf-830e-c990151ec258" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_bad93eee-2f15-4b1f-ad00-4394248ac1ba" xlink:to="loc_us-gaap_SubsequentEventMember_ed6bfa10-30fe-4acf-830e-c990151ec258" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesAuthorized_c31d716d-860f-4e74-90cc-55429c6d322a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquitySharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TemporaryEquitySharesAuthorized_c31d716d-860f-4e74-90cc-55429c6d322a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_83ea4e43-91db-4720-b9ce-51871ceaaf43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_83ea4e43-91db-4720-b9ce-51871ceaaf43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPrivatePlacement_93e033b5-bc96-4d32-ba4d-17ab66bc0ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfPrivatePlacement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPrivatePlacement_93e033b5-bc96-4d32-ba4d-17ab66bc0ebc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_bfec8cea-a407-4540-a28b-4b4d3ed5cc4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_bfec8cea-a407-4540-a28b-4b4d3ed5cc4b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquitySharesConversionOfConvertibleSecurities_60f25d56-e44d-49d3-bb2b-7ef29b72c805" xlink:href="wdc-20250627.xsd#wdc_TemporaryEquitySharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_TemporaryEquitySharesConversionOfConvertibleSecurities_60f25d56-e44d-49d3-bb2b-7ef29b72c805" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_7241fad1-c874-484f-8a21-9a96e0eebbbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_7241fad1-c874-484f-8a21-9a96e0eebbbf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_417295b5-2b2f-4893-8e24-f248b6bf096a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_417295b5-2b2f-4893-8e24-f248b6bf096a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquityPreferredStockDividendRatePercentage_3796558b-68e4-4f4e-bba5-8655dc48e760" xlink:href="wdc-20250627.xsd#wdc_TemporaryEquityPreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_TemporaryEquityPreferredStockDividendRatePercentage_3796558b-68e4-4f4e-bba5-8655dc48e760" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStock_668bd728-6a35-4949-a896-3a32eedd8743" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_DividendsPreferredStock_668bd728-6a35-4949-a896-3a32eedd8743" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CumulativeDividends_2340e09e-2f01-4ce7-b4f7-64e810285051" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CumulativeDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_CumulativeDividends_2340e09e-2f01-4ce7-b4f7-64e810285051" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockConvertibleConversionPrice_16e6edf3-86cc-49e4-9a7b-e933af116854" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockConvertibleConversionPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_PreferredStockConvertibleConversionPrice_16e6edf3-86cc-49e4-9a7b-e933af116854" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockConvertibleConversionRatio_cccd4cbc-b13b-483b-bbaf-59df3dea458f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockConvertibleConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_PreferredStockConvertibleConversionRatio_cccd4cbc-b13b-483b-bbaf-59df3dea458f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PreferredStockConvertibleThresholdConsecutiveTradingDays_9a4f3024-56d6-4a35-9c97-a0de043475a1" xlink:href="wdc-20250627.xsd#wdc_PreferredStockConvertibleThresholdConsecutiveTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_PreferredStockConvertibleThresholdConsecutiveTradingDays_9a4f3024-56d6-4a35-9c97-a0de043475a1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PreferredStockConvertibleConversionPricePercentage_1aa3df99-badb-4965-a012-4e2f172e3805" xlink:href="wdc-20250627.xsd#wdc_PreferredStockConvertibleConversionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_PreferredStockConvertibleConversionPricePercentage_1aa3df99-badb-4965-a012-4e2f172e3805" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CommonStockOutstandingPotentialConvertible_a0d684dc-3cdc-4767-a7cf-3c94e7e2bed7" xlink:href="wdc-20250627.xsd#wdc_CommonStockOutstandingPotentialConvertible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_CommonStockOutstandingPotentialConvertible_a0d684dc-3cdc-4767-a7cf-3c94e7e2bed7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_PreferredStockRedemptionAccumulatedStatedValuePercentage_d9404b8a-f777-4f17-9b32-29f2297d5236" xlink:href="wdc-20250627.xsd#wdc_PreferredStockRedemptionAccumulatedStatedValuePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_wdc_PreferredStockRedemptionAccumulatedStatedValuePercentage_d9404b8a-f777-4f17-9b32-29f2297d5236" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLiquidationPreference_8f27094c-2a02-439c-89df-54bb86f0cf1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TemporaryEquityLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TemporaryEquityLiquidationPreference_8f27094c-2a02-439c-89df-54bb86f0cf1d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_0dd9f456-7464-4657-b9f6-222005d3e95b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_0dd9f456-7464-4657-b9f6-222005d3e95b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_5d3aea3a-f53a-4b71-bb9f-862e7138da5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_5d3aea3a-f53a-4b71-bb9f-862e7138da5b" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_15358e1d-63a6-4b81-84d7-485ff4e405a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_15358e1d-63a6-4b81-84d7-485ff4e405a9" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_adf1e0c5-923c-4cae-88b8-45f2db1c7dec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_adf1e0c5-923c-4cae-88b8-45f2db1c7dec" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_6accc7ac-bc3f-42c2-bad1-b6c1657c7701" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_6accc7ac-bc3f-42c2-bad1-b6c1657c7701" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfOrdinaryDividends_c2f0dc4f-f869-4d83-a0c5-8f2627f13350" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfOrdinaryDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76551b4f-583a-4b69-84eb-fa0b15c21116" xlink:to="loc_us-gaap_PaymentsOfOrdinaryDividends_c2f0dc4f-f869-4d83-a0c5-8f2627f13350" xlink:type="arc" order="22"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockStockReservedforIssuanceDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#ShareholdersEquityandConvertiblePreferredStockStockReservedforIssuanceDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockStockReservedforIssuanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_137e3e21-ef58-4617-8969-8aae5c2cac54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8898a35e-ec30-45ee-931d-cf9fac8be61e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_137e3e21-ef58-4617-8969-8aae5c2cac54" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8898a35e-ec30-45ee-931d-cf9fac8be61e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_48834d9e-b6cb-403b-ab72-68038e475c95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8898a35e-ec30-45ee-931d-cf9fac8be61e" xlink:to="loc_us-gaap_AwardTypeAxis_48834d9e-b6cb-403b-ab72-68038e475c95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_48834d9e-b6cb-403b-ab72-68038e475c95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_48834d9e-b6cb-403b-ab72-68038e475c95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_48834d9e-b6cb-403b-ab72-68038e475c95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_48834d9e-b6cb-403b-ab72-68038e475c95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_27b5b802-7e20-42ad-876a-78177e180d35" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:to="loc_us-gaap_ConvertibleDebtMember_27b5b802-7e20-42ad-876a-78177e180d35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_OutstandingAwardsAndSharesAvailableForAwardMember_615d3a20-5614-4ab0-9e3b-064dec9c36a2" xlink:href="wdc-20250627.xsd#wdc_OutstandingAwardsAndSharesAvailableForAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:to="loc_wdc_OutstandingAwardsAndSharesAvailableForAwardMember_615d3a20-5614-4ab0-9e3b-064dec9c36a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_fd136922-5270-48a3-af5f-6825a0ea7a45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_fd136922-5270-48a3-af5f-6825a0ea7a45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_43b977f0-e50d-4465-b862-7dc94741c6b9" xlink:href="wdc-20250627.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78fae7d8-c8c8-4cee-823a-eb9e5a5fa682" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_43b977f0-e50d-4465-b862-7dc94741c6b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_0c51231a-ec31-4a71-8af8-b7a057b47f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_137e3e21-ef58-4617-8969-8aae5c2cac54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_0c51231a-ec31-4a71-8af8-b7a057b47f2a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/IncomeTaxExpenseAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#IncomeTaxExpenseAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/IncomeTaxExpenseAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:href="wdc-20250627.xsd#wdc_IncomeTaxDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_IncomeTaxDisclosureTable_31070ca3-815f-46ff-ba4b-e6d80a7a6718" xlink:href="wdc-20250627.xsd#wdc_IncomeTaxDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_IncomeTaxDisclosureTable_31070ca3-815f-46ff-ba4b-e6d80a7a6718" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_eafecdc4-3e70-4b4c-9d37-5fc4a4569707" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_wdc_IncomeTaxDisclosureTable_31070ca3-815f-46ff-ba4b-e6d80a7a6718" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_eafecdc4-3e70-4b4c-9d37-5fc4a4569707" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_eafecdc4-3e70-4b4c-9d37-5fc4a4569707_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_eafecdc4-3e70-4b4c-9d37-5fc4a4569707" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_eafecdc4-3e70-4b4c-9d37-5fc4a4569707_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_140c8e72-6de4-47b4-b4e5-8e1081d0a2e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_eafecdc4-3e70-4b4c-9d37-5fc4a4569707" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_140c8e72-6de4-47b4-b4e5-8e1081d0a2e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_6c56bc64-baac-44e9-8ee1-dc107809155d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_140c8e72-6de4-47b4-b4e5-8e1081d0a2e8" xlink:to="loc_us-gaap_DomesticCountryMember_6c56bc64-baac-44e9-8ee1-dc107809155d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_9fbb3bbd-f6b7-47e9-a157-c8052fae9a50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_140c8e72-6de4-47b4-b4e5-8e1081d0a2e8" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_9fbb3bbd-f6b7-47e9-a157-c8052fae9a50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b38047ed-7f46-4d64-8ee5-cd5904799203" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_wdc_IncomeTaxDisclosureTable_31070ca3-815f-46ff-ba4b-e6d80a7a6718" xlink:to="loc_srt_RangeAxis_b38047ed-7f46-4d64-8ee5-cd5904799203" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b38047ed-7f46-4d64-8ee5-cd5904799203_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b38047ed-7f46-4d64-8ee5-cd5904799203" xlink:to="loc_srt_RangeMember_b38047ed-7f46-4d64-8ee5-cd5904799203_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_aecb3dd5-050b-49ca-9c56-ff885ff4f3df" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b38047ed-7f46-4d64-8ee5-cd5904799203" xlink:to="loc_srt_RangeMember_aecb3dd5-050b-49ca-9c56-ff885ff4f3df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a11528b7-a05e-44c3-a29d-54378ec5e9c5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_aecb3dd5-050b-49ca-9c56-ff885ff4f3df" xlink:to="loc_srt_MinimumMember_a11528b7-a05e-44c3-a29d-54378ec5e9c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_434d68db-23be-4a6b-881e-4b758eeb1c48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_wdc_IncomeTaxDisclosureTable_31070ca3-815f-46ff-ba4b-e6d80a7a6718" xlink:to="loc_us-gaap_TaxPeriodAxis_434d68db-23be-4a6b-881e-4b758eeb1c48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_434d68db-23be-4a6b-881e-4b758eeb1c48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_434d68db-23be-4a6b-881e-4b758eeb1c48" xlink:to="loc_us-gaap_TaxPeriodDomain_434d68db-23be-4a6b-881e-4b758eeb1c48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_7571a221-91a3-4352-9f90-b16055ec8bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_434d68db-23be-4a6b-881e-4b758eeb1c48" xlink:to="loc_us-gaap_TaxPeriodDomain_7571a221-91a3-4352-9f90-b16055ec8bf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxYears2008Through2012Member_eed34ef0-c35e-4a48-9a3f-871f86076c1a" xlink:href="wdc-20250627.xsd#wdc_TaxYears2008Through2012Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_7571a221-91a3-4352-9f90-b16055ec8bf6" xlink:to="loc_wdc_TaxYears2008Through2012Member_eed34ef0-c35e-4a48-9a3f-871f86076c1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxYears2013Through2015Member_a0c50654-16f3-459e-9b11-b4f2f5541f86" xlink:href="wdc-20250627.xsd#wdc_TaxYears2013Through2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_7571a221-91a3-4352-9f90-b16055ec8bf6" xlink:to="loc_wdc_TaxYears2013Through2015Member_a0c50654-16f3-459e-9b11-b4f2f5541f86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxYears2008Through2015Member_a0b9896f-87b7-46dd-ab92-4cdabf6fc26d" xlink:href="wdc-20250627.xsd#wdc_TaxYears2008Through2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_7571a221-91a3-4352-9f90-b16055ec8bf6" xlink:to="loc_wdc_TaxYears2008Through2015Member_a0b9896f-87b7-46dd-ab92-4cdabf6fc26d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxHolidayAggregateDollarAmount_d8e1d236-4a35-491f-8ad2-a6e2147c1a42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxHolidayAggregateDollarAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_IncomeTaxHolidayAggregateDollarAmount_d8e1d236-4a35-491f-8ad2-a6e2147c1a42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare_33ac35db-bcd6-4a19-962d-18c16b0f9702" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare_33ac35db-bcd6-4a19-962d-18c16b0f9702" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_5d937302-4787-4c2c-9dd8-51edfa91c85b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_5d937302-4787-4c2c-9dd8-51edfa91c85b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardValuationAllowance_28acc585-34c5-4867-a651-d905a27987f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_TaxCreditCarryforwardValuationAllowance_28acc585-34c5-4867-a651-d905a27987f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_710df2cf-fa96-4b56-b7d6-2545f5ec8cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_710df2cf-fa96-4b56-b7d6-2545f5ec8cbd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_382207d9-7113-4cc0-b771-ba88f552b7c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_382207d9-7113-4cc0-b771-ba88f552b7c9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsIncludingAccruedInterestAndPenalties_c8aab8b9-f6c9-4fba-8643-a0430a876dec" xlink:href="wdc-20250627.xsd#wdc_UnrecognizedTaxBenefitsIncludingAccruedInterestAndPenalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_UnrecognizedTaxBenefitsIncludingAccruedInterestAndPenalties_c8aab8b9-f6c9-4fba-8643-a0430a876dec" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_23dd3a8a-218b-4608-87f0-10379508f411" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_TaxesPayableCurrent_23dd3a8a-218b-4608-87f0-10379508f411" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsFavorableTaxReceivable_71bdab5f-8615-4fb2-8607-91151efcf39b" xlink:href="wdc-20250627.xsd#wdc_UnrecognizedTaxBenefitsFavorableTaxReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_UnrecognizedTaxBenefitsFavorableTaxReceivable_71bdab5f-8615-4fb2-8607-91151efcf39b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsNetPotentialPayment_e5d060b3-9c59-4761-a62b-186f0464a489" xlink:href="wdc-20250627.xsd#wdc_UnrecognizedTaxBenefitsNetPotentialPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_UnrecognizedTaxBenefitsNetPotentialPayment_e5d060b3-9c59-4761-a62b-186f0464a489" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense_e0758716-6373-4ca8-9121-0926c436f30d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense_e0758716-6373-4ca8-9121-0926c436f30d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationInterestExpense_e48b3681-d49d-4b02-a326-c6e5259baf72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExaminationInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_us-gaap_IncomeTaxExaminationInterestExpense_e48b3681-d49d-4b02-a326-c6e5259baf72" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability_1927388f-cbeb-4b53-ba98-b2659d17d788" xlink:href="wdc-20250627.xsd#wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability_1927388f-cbeb-4b53-ba98-b2659d17d788" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DeferredTaxAssetMandatoryDeemedRepatriationLiability_69fe5916-eddb-4c31-ad26-db546412af5c" xlink:href="wdc-20250627.xsd#wdc_DeferredTaxAssetMandatoryDeemedRepatriationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_wdc_IncomeTaxDisclosureLineItems_71145487-5037-4e74-a20e-bb9cf97ff09b" xlink:to="loc_wdc_DeferredTaxAssetMandatoryDeemedRepatriationLiability_69fe5916-eddb-4c31-ad26-db546412af5c" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/IncomeTaxExpenseNOLCarryforwardDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#IncomeTaxExpenseNOLCarryforwardDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/IncomeTaxExpenseNOLCarryforwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_aff8458c-63ff-4096-9949-39d7c8be0fb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_0e0d8068-63d8-4b6e-9c95-ec22244c560c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_aff8458c-63ff-4096-9949-39d7c8be0fb4" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_0e0d8068-63d8-4b6e-9c95-ec22244c560c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_944589d5-506f-482b-ab7c-8050691d6872" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_0e0d8068-63d8-4b6e-9c95-ec22244c560c" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_944589d5-506f-482b-ab7c-8050691d6872" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_944589d5-506f-482b-ab7c-8050691d6872_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_944589d5-506f-482b-ab7c-8050691d6872" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_944589d5-506f-482b-ab7c-8050691d6872_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_944589d5-506f-482b-ab7c-8050691d6872" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DomesticTaxAuthorityPre2017ActGenerationMember_2c2a85be-f3b1-477e-b603-b6754563b795" xlink:href="wdc-20250627.xsd#wdc_DomesticTaxAuthorityPre2017ActGenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:to="loc_wdc_DomesticTaxAuthorityPre2017ActGenerationMember_2c2a85be-f3b1-477e-b603-b6754563b795" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_DomesticTaxAuthorityPost2017ActGenerationMember_4f2077dc-0556-4fc1-9d02-4afe88758fd6" xlink:href="wdc-20250627.xsd#wdc_DomesticTaxAuthorityPost2017ActGenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:to="loc_wdc_DomesticTaxAuthorityPost2017ActGenerationMember_4f2077dc-0556-4fc1-9d02-4afe88758fd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_8996198b-53ca-4b54-b55f-25b2cd15db38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_8996198b-53ca-4b54-b55f-25b2cd15db38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_32d97847-9ab1-447a-aa7f-6f16d983c848" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_20b5ad30-4157-4f37-8d42-3be7de518b69" xlink:to="loc_us-gaap_DomesticCountryMember_32d97847-9ab1-447a-aa7f-6f16d983c848" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_91ecaef5-dd23-4970-8553-fb74e11732ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_0e0d8068-63d8-4b6e-9c95-ec22244c560c" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_91ecaef5-dd23-4970-8553-fb74e11732ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_91ecaef5-dd23-4970-8553-fb74e11732ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_91ecaef5-dd23-4970-8553-fb74e11732ad" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_91ecaef5-dd23-4970-8553-fb74e11732ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_823e16f3-c6b6-421b-ae48-7fd9bcaf58a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_91ecaef5-dd23-4970-8553-fb74e11732ad" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_823e16f3-c6b6-421b-ae48-7fd9bcaf58a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxAuthorityMalaysiaMember_3a566618-388c-432d-898b-f8f3b23f3536" xlink:href="wdc-20250627.xsd#wdc_TaxAuthorityMalaysiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_823e16f3-c6b6-421b-ae48-7fd9bcaf58a8" xlink:to="loc_wdc_TaxAuthorityMalaysiaMember_3a566618-388c-432d-898b-f8f3b23f3536" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NationalTaxAgencyJapanMember_4d4baaa0-2264-453a-917a-03fc12c37798" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NationalTaxAgencyJapanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_823e16f3-c6b6-421b-ae48-7fd9bcaf58a8" xlink:to="loc_us-gaap_NationalTaxAgencyJapanMember_4d4baaa0-2264-453a-917a-03fc12c37798" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_f7b2ff84-d82b-4996-a431-9a2b06a70ee7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_aff8458c-63ff-4096-9949-39d7c8be0fb4" xlink:to="loc_us-gaap_OperatingLossCarryforwards_f7b2ff84-d82b-4996-a431-9a2b06a70ee7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_3d101d0f-9239-48ef-a7b1-9eeec11ef904" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_aff8458c-63ff-4096-9949-39d7c8be0fb4" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_3d101d0f-9239-48ef-a7b1-9eeec11ef904" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/BusinessRealignmentChargesExpenseRecognitionDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#BusinessRealignmentChargesExpenseRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/BusinessRealignmentChargesExpenseRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_073dfa66-f47b-4744-be7f-c8409d7dbe76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_073dfa66-f47b-4744-be7f-c8409d7dbe76" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_a156d056-6f26-49fe-bd3a-3046a12b2325" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_073dfa66-f47b-4744-be7f-c8409d7dbe76" xlink:to="loc_us-gaap_RestructuringPlanAxis_a156d056-6f26-49fe-bd3a-3046a12b2325" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_a156d056-6f26-49fe-bd3a-3046a12b2325_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_a156d056-6f26-49fe-bd3a-3046a12b2325" xlink:to="loc_us-gaap_RestructuringPlanDomain_a156d056-6f26-49fe-bd3a-3046a12b2325_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_961c40a4-3094-4c11-aa6c-f93224608599" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_a156d056-6f26-49fe-bd3a-3046a12b2325" xlink:to="loc_us-gaap_RestructuringPlanDomain_961c40a4-3094-4c11-aa6c-f93224608599" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentActivitiesMember_8d46a3a0-5c60-49df-ab82-3d36bc048eb2" xlink:href="wdc-20250627.xsd#wdc_BusinessRealignmentActivitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_961c40a4-3094-4c11-aa6c-f93224608599" xlink:to="loc_wdc_BusinessRealignmentActivitiesMember_8d46a3a0-5c60-49df-ab82-3d36bc048eb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeTerminationBenefitsAndOtherContractTerminationCosts_ef43242d-2edf-4088-bccc-1d4dde2c1870" xlink:href="wdc-20250627.xsd#wdc_EmployeeTerminationBenefitsAndOtherContractTerminationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_wdc_EmployeeTerminationBenefitsAndOtherContractTerminationCosts_ef43242d-2edf-4088-bccc-1d4dde2c1870" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_4d6d42f2-2aa8-461d-be74-0620d89c4038" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_us-gaap_AssetImpairmentCharges_4d6d42f2-2aa8-461d-be74-0620d89c4038" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_d8ab88e6-a87a-435c-bab0-d0e5e33eefb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_d8ab88e6-a87a-435c-bab0-d0e5e33eefb6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossOnContractTermination_ed508daf-2af3-4a05-9618-7aacf2263255" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossOnContractTermination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_us-gaap_LossOnContractTermination_ed508daf-2af3-4a05-9618-7aacf2263255" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RecoveryOfNonCancellablePurchaseOrder_e860487b-122b-4fcf-945e-88047b889ff5" xlink:href="wdc-20250627.xsd#wdc_RecoveryOfNonCancellablePurchaseOrder"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_wdc_RecoveryOfNonCancellablePurchaseOrder_e860487b-122b-4fcf-945e-88047b889ff5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_ab8df9db-cc0c-4589-82da-25d40344e07d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_43e3a883-21ca-4c8a-9324-49bf08b61031" xlink:to="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_ab8df9db-cc0c-4589-82da-25d40344e07d" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/BusinessRealignmentChargesBusinessRealignmentActivitiesDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#BusinessRealignmentChargesBusinessRealignmentActivitiesDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/BusinessRealignmentChargesBusinessRealignmentActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_8c59134c-50bd-409a-810f-8d3c9fca0eeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_87df64e6-84dc-4065-b048-96b49e86fc22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_8c59134c-50bd-409a-810f-8d3c9fca0eeb" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_87df64e6-84dc-4065-b048-96b49e86fc22" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_73a69b9e-6bda-45bd-8fae-86fd277058db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_87df64e6-84dc-4065-b048-96b49e86fc22" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_73a69b9e-6bda-45bd-8fae-86fd277058db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_73a69b9e-6bda-45bd-8fae-86fd277058db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_73a69b9e-6bda-45bd-8fae-86fd277058db" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_73a69b9e-6bda-45bd-8fae-86fd277058db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_f96380d4-87f7-40d3-8cc2-a92e46b1b922" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_73a69b9e-6bda-45bd-8fae-86fd277058db" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_f96380d4-87f7-40d3-8cc2-a92e46b1b922" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OneTimeTerminationBenefitsMember_11b128a4-251b-46cd-9672-881a645fbe77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OneTimeTerminationBenefitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_f96380d4-87f7-40d3-8cc2-a92e46b1b922" xlink:to="loc_us-gaap_OneTimeTerminationBenefitsMember_11b128a4-251b-46cd-9672-881a645fbe77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractTerminationMember_f956c930-4230-4bf4-9708-00add9274d12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractTerminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_f96380d4-87f7-40d3-8cc2-a92e46b1b922" xlink:to="loc_us-gaap_ContractTerminationMember_f956c930-4230-4bf4-9708-00add9274d12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_87df64e6-84dc-4065-b048-96b49e86fc22" xlink:to="loc_us-gaap_RestructuringPlanAxis_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf" xlink:to="loc_us-gaap_RestructuringPlanDomain_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_bcd26724-18db-442d-ba9d-6361d13411bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_ab97a58d-1d4c-4ec2-b3da-0f24f4c988cf" xlink:to="loc_us-gaap_RestructuringPlanDomain_bcd26724-18db-442d-ba9d-6361d13411bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentActivitiesMember_add57fc9-7ede-4da3-bf9d-dd70a46fef7c" xlink:href="wdc-20250627.xsd#wdc_BusinessRealignmentActivitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_bcd26724-18db-442d-ba9d-6361d13411bb" xlink:to="loc_wdc_BusinessRealignmentActivitiesMember_add57fc9-7ede-4da3-bf9d-dd70a46fef7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_8c59134c-50bd-409a-810f-8d3c9fca0eeb" xlink:to="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_6cce5751-8218-4574-8db1-60373d50b969" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:to="loc_us-gaap_RestructuringReserve_6cce5751-8218-4574-8db1-60373d50b969" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_0f0efa39-8c8d-4798-8e87-2472379e33bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:to="loc_us-gaap_RestructuringCharges_0f0efa39-8c8d-4798-8e87-2472379e33bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_23bf7e3b-e457-4977-8468-c75eb7b22e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:to="loc_us-gaap_PaymentsForRestructuring_23bf7e3b-e457-4977-8468-c75eb7b22e1f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RecoveryOfNonCancellablePurchaseOrder_6fc09f7b-9876-4d2b-b041-dc0729c913aa" xlink:href="wdc-20250627.xsd#wdc_RecoveryOfNonCancellablePurchaseOrder"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_3950e18e-a306-4b0c-a5b5-44589e680af7" xlink:to="loc_wdc_RecoveryOfNonCancellablePurchaseOrder_6fc09f7b-9876-4d2b-b041-dc0729c913aa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_81c89551-2fcc-4a86-b043-df7edaf8f022" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplierFinanceProgramNarrativeDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#SupplierFinanceProgramNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplierFinanceProgramNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramLineItems_a494738c-7848-4e1b-9be3-ca3152d23003" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramTable_c2cf41dc-7d28-4019-84b9-5335900e9aae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_a494738c-7848-4e1b-9be3-ca3152d23003" xlink:to="loc_us-gaap_SupplierFinanceProgramTable_c2cf41dc-7d28-4019-84b9-5335900e9aae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ed262078-39ae-41d0-9a52-485d43686a98" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SupplierFinanceProgramTable_c2cf41dc-7d28-4019-84b9-5335900e9aae" xlink:to="loc_srt_RangeAxis_ed262078-39ae-41d0-9a52-485d43686a98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ed262078-39ae-41d0-9a52-485d43686a98_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ed262078-39ae-41d0-9a52-485d43686a98" xlink:to="loc_srt_RangeMember_ed262078-39ae-41d0-9a52-485d43686a98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_dca8aa3d-37b3-4ff9-a723-7aa2d99852a7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ed262078-39ae-41d0-9a52-485d43686a98" xlink:to="loc_srt_RangeMember_dca8aa3d-37b3-4ff9-a723-7aa2d99852a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5dd40c61-c247-4402-8b89-4a8af6c807c1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_dca8aa3d-37b3-4ff9-a723-7aa2d99852a7" xlink:to="loc_srt_MinimumMember_5dd40c61-c247-4402-8b89-4a8af6c807c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1aea7160-5743-4459-9d1e-e3088985e1d8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_dca8aa3d-37b3-4ff9-a723-7aa2d99852a7" xlink:to="loc_srt_MaximumMember_1aea7160-5743-4459-9d1e-e3088985e1d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramPaymentTimingPeriod_bf31e8fa-6873-464c-98e5-3a2900c60212" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramPaymentTimingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_a494738c-7848-4e1b-9be3-ca3152d23003" xlink:to="loc_us-gaap_SupplierFinanceProgramPaymentTimingPeriod_bf31e8fa-6873-464c-98e5-3a2900c60212" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramObligationCurrent_ead24b9d-8456-4817-a248-36e20fa4f8f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramObligationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_a494738c-7848-4e1b-9be3-ca3152d23003" xlink:to="loc_us-gaap_SupplierFinanceProgramObligationCurrent_ead24b9d-8456-4817-a248-36e20fa4f8f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramObligationCurrentStatementOfFinancialPositionExtensibleEnumeration_cab598bd-5353-4337-8059-0afb04ed09b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramObligationCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_a494738c-7848-4e1b-9be3-ca3152d23003" xlink:to="loc_us-gaap_SupplierFinanceProgramObligationCurrentStatementOfFinancialPositionExtensibleEnumeration_cab598bd-5353-4337-8059-0afb04ed09b0" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/LegalProceedingsAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20250627.xsd#LegalProceedingsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/LegalProceedingsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_6220827c-534d-4ed3-9fa4-f7d148f200b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingenciesTable_6220827c-534d-4ed3-9fa4-f7d148f200b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_6220827c-534d-4ed3-9fa4-f7d148f200b4" xlink:to="loc_srt_LitigationCaseAxis_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc" xlink:to="loc_srt_LitigationCaseTypeDomain_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_0716623d-7619-4626-8bdb-c8079ea8250d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_f3d1bbb6-d9f7-4bd8-8c85-6d81761bb8cc" xlink:to="loc_srt_LitigationCaseTypeDomain_0716623d-7619-4626-8bdb-c8079ea8250d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_IntellectualPropertyLitigationMember_0da73d38-2c6f-4362-86eb-1740729e11dc" xlink:href="wdc-20250627.xsd#wdc_IntellectualPropertyLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_0716623d-7619-4626-8bdb-c8079ea8250d" xlink:to="loc_wdc_IntellectualPropertyLitigationMember_0da73d38-2c6f-4362-86eb-1740729e11dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SPEXTechnologiesInc.LawsuitMember_e779e764-dc6e-460a-afe5-b7e896c4670a" xlink:href="wdc-20250627.xsd#wdc_SPEXTechnologiesInc.LawsuitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_0716623d-7619-4626-8bdb-c8079ea8250d" xlink:to="loc_wdc_SPEXTechnologiesInc.LawsuitMember_e779e764-dc6e-460a-afe5-b7e896c4670a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_836fac99-6410-4000-b2b6-a426f2aefd5e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_6220827c-534d-4ed3-9fa4-f7d148f200b4" xlink:to="loc_dei_LegalEntityAxis_836fac99-6410-4000-b2b6-a426f2aefd5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_836fac99-6410-4000-b2b6-a426f2aefd5e_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_836fac99-6410-4000-b2b6-a426f2aefd5e" xlink:to="loc_dei_EntityDomain_836fac99-6410-4000-b2b6-a426f2aefd5e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_ad35ab73-dce5-466f-b79f-eb362050d3e7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_836fac99-6410-4000-b2b6-a426f2aefd5e" xlink:to="loc_dei_EntityDomain_ad35ab73-dce5-466f-b79f-eb362050d3e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_MRTechnologiesGmbHMember_87a2a541-3b83-453e-820f-10525c4c7693" xlink:href="wdc-20250627.xsd#wdc_MRTechnologiesGmbHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_ad35ab73-dce5-466f-b79f-eb362050d3e7" xlink:to="loc_wdc_MRTechnologiesGmbHMember_87a2a541-3b83-453e-820f-10525c4c7693" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_6b6f40de-df62-4b36-94ec-32e7ab0239f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_6220827c-534d-4ed3-9fa4-f7d148f200b4" xlink:to="loc_us-gaap_LitigationStatusAxis_6b6f40de-df62-4b36-94ec-32e7ab0239f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_6b6f40de-df62-4b36-94ec-32e7ab0239f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_6b6f40de-df62-4b36-94ec-32e7ab0239f1" xlink:to="loc_us-gaap_LitigationStatusDomain_6b6f40de-df62-4b36-94ec-32e7ab0239f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_3bf0b03c-343e-47b6-9e60-c1f7c26a0fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_6b6f40de-df62-4b36-94ec-32e7ab0239f1" xlink:to="loc_us-gaap_LitigationStatusDomain_3bf0b03c-343e-47b6-9e60-c1f7c26a0fb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_691e798f-4069-4d0f-a39e-cec1755575e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_3bf0b03c-343e-47b6-9e60-c1f7c26a0fb8" xlink:to="loc_us-gaap_PendingLitigationMember_691e798f-4069-4d0f-a39e-cec1755575e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettledLitigationMember_4ab8ee87-3f0a-43bf-b96b-65e7793c546b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SettledLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_3bf0b03c-343e-47b6-9e60-c1f7c26a0fb8" xlink:to="loc_us-gaap_SettledLitigationMember_4ab8ee87-3f0a-43bf-b96b-65e7793c546b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPatentsAllegedlyInfringedNumber_2003f435-9027-4b4d-b4e8-1b07d2bf6d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyPatentsAllegedlyInfringedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingencyPatentsAllegedlyInfringedNumber_2003f435-9027-4b4d-b4e8-1b07d2bf6d5e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_84eefa21-e895-4ec8-877f-edce0150c3f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_84eefa21-e895-4ec8-877f-edce0150c3f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_83c7d964-d47d-4339-8c70-4412635626a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_83c7d964-d47d-4339-8c70-4412635626a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_7e72cb6c-cbd4-4367-8a67-4720ecf1b423" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualCarryingValueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_7e72cb6c-cbd4-4367-8a67-4720ecf1b423" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementLoss_dbb1dc5d-76d3-484b-afb0-eea4f58ee7cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationSettlementLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LitigationSettlementLoss_dbb1dc5d-76d3-484b-afb0-eea4f58ee7cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedPatentsGross_685eb78a-4880-4d9a-81cc-7b732123c25e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedPatentsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_FiniteLivedPatentsGross_685eb78a-4880-4d9a-81cc-7b732123c25e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_d62615b3-3afa-4332-b4ee-aa79615da268" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_d62615b3-3afa-4332-b4ee-aa79615da268" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementGain_51bd8d85-14dc-4dfb-a177-b9ebcf00f454" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationSettlementGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LitigationSettlementGain_51bd8d85-14dc-4dfb-a177-b9ebcf00f454" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_f516c9d7-1e14-457a-87a6-5fc85811d420" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_f516c9d7-1e14-457a-87a6-5fc85811d420" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_b60efe9c-8458-4972-bc97-6a4735336a2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_b60efe9c-8458-4972-bc97-6a4735336a2f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementInterest_650b7776-5127-415e-a71f-50e2415c3672" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationSettlementInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b60364b6-6d84-4129-8e98-d6c092f1d0ab" xlink:to="loc_us-gaap_LitigationSettlementInterest_650b7776-5127-415e-a71f-50e2415c3672" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="101"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:type="arc" order="41"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_us-gaap_AccountsPayableCurrent" xlink:type="arc" order="42"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_IrvingTanMember_ef284db5-9376-4ce7-8725-210ab3224089" xlink:href="wdc-20250627.xsd#wdc_IrvingTanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_wdc_IrvingTanMember_ef284db5-9376-4ce7-8725-210ab3224089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CynthiaTregillisMember_27b5f038-6c88-4342-a259-c761af23c611" xlink:href="wdc-20250627.xsd#wdc_CynthiaTregillisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_wdc_CynthiaTregillisMember_27b5f038-6c88-4342-a259-c761af23c611" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
