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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019fa4db-741f-7024-b2dc-de52fc9a9af4,g:b1fb4509-3cef-4ea0-becf-041534e61cd4-->
<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.molinahealthcare.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="moh-20260930.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fa4db-7591-757d-b10b-f80d70c1b89e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fa4db-7591-7421-98a8-f7bf0cf28b13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fa4db-7591-757d-b10b-f80d70c1b89e" xlink:to="loc_us-gaap_StatementTable_019fa4db-7591-7421-98a8-f7bf0cf28b13" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019fa4db-7591-7bef-8513-139876b3382c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fa4db-7591-7421-98a8-f7bf0cf28b13" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019fa4db-7591-7bef-8513-139876b3382c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7bef-8513-139876b3382c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fa4db-7591-7bef-8513-139876b3382c" xlink:to="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7bef-8513-139876b3382c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fa4db-7591-7bef-8513-139876b3382c" xlink:to="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019fa4db-7591-7499-a753-f70c96381b75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:to="loc_us-gaap_CommonStockMember_019fa4db-7591-7499-a753-f70c96381b75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019fa4db-7591-7bb1-bbc5-97e15df121d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019fa4db-7591-7bb1-bbc5-97e15df121d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fa4db-7591-7c81-974d-32dc50864244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fa4db-7591-7c81-974d-32dc50864244" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019fa4db-7591-7256-9010-4add213a7f54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fa4db-7591-7d7b-9da0-6e84b2a0594a" xlink:to="loc_us-gaap_RetainedEarningsMember_019fa4db-7591-7256-9010-4add213a7f54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fa4db-7591-757d-b10b-f80d70c1b89e" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fa4db-7591-7ff5-92e4-946d3f0458bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019fa4db-7591-7ff5-92e4-946d3f0458bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fa4db-7591-788b-a9a2-adbea3c88a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_StockholdersEquity_019fa4db-7591-788b-a9a2-adbea3c88a6f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fa4db-7591-7515-81e2-637bd63f979e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_NetIncomeLoss_019fa4db-7591-7515-81e2-637bd63f979e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fa4db-7591-7c1f-8e77-d50123696314" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fa4db-7591-7c1f-8e77-d50123696314" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fa4db-7591-799c-afe7-2e8594791e28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fa4db-7591-799c-afe7-2e8594791e28" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fa4db-7591-737d-8420-3a506a21e435" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareRepurchaseProgramExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fa4db-7591-737d-8420-3a506a21e435" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019fa4db-7591-741a-9652-ce312884e268" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019fa4db-7591-741a-9652-ce312884e268" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fa4db-7591-7bf6-b40a-4616a61d1821" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fa4db-7591-7bf6-b40a-4616a61d1821" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019fa4db-7591-71e0-8dc8-27169ede472c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fa4db-7591-756d-a989-c36d84ba41b5" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019fa4db-7591-71e0-8dc8-27169ede472c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fa4db-7591-787d-86d7-eb8ed80de3f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fa4db-7591-772a-aed4-9f687f9253ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/OrganizationandBasisofPresentationDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#OrganizationandBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/OrganizationandBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:href="moh-20260930.xsd#moh_BasisOfPresentationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_BasisOfPresentationTable_019fa4db-7591-78ad-acd6-a9f8bd3091e5" xlink:href="moh-20260930.xsd#moh_BasisOfPresentationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:to="loc_moh_BasisOfPresentationTable_019fa4db-7591-78ad-acd6-a9f8bd3091e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7591-780d-8638-a43e70004b23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_moh_BasisOfPresentationTable_019fa4db-7591-78ad-acd6-a9f8bd3091e5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7591-780d-8638-a43e70004b23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7591-780d-8638-a43e70004b23_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7591-780d-8638-a43e70004b23" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7591-780d-8638-a43e70004b23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7591-7b7d-98be-7cdb48699840" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7591-780d-8638-a43e70004b23" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7591-7b7d-98be-7cdb48699840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_HealthPlansMember_019fa4db-7591-7eee-819b-bbd30b8d0557" xlink:href="moh-20260930.xsd#moh_HealthPlansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7591-7b7d-98be-7cdb48699840" xlink:to="loc_moh_HealthPlansMember_019fa4db-7591-7eee-819b-bbd30b8d0557" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019fa4db-7591-76ec-a7d8-f3c37119f110" xlink:href="moh-20260930.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7591-7b7d-98be-7cdb48699840" xlink:to="loc_moh_MedicaidMember_019fa4db-7591-76ec-a7d8-f3c37119f110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019fa4db-7591-7395-aafa-c5e50ebf7b01" xlink:href="moh-20260930.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7591-7b7d-98be-7cdb48699840" xlink:to="loc_moh_MedicareMember_019fa4db-7591-7395-aafa-c5e50ebf7b01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fa4db-7591-7501-b64a-5d738fb3cc64" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_moh_BasisOfPresentationTable_019fa4db-7591-78ad-acd6-a9f8bd3091e5" xlink:to="loc_srt_RangeAxis_019fa4db-7591-7501-b64a-5d738fb3cc64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fa4db-7591-7501-b64a-5d738fb3cc64_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fa4db-7591-7501-b64a-5d738fb3cc64" xlink:to="loc_srt_RangeMember_019fa4db-7591-7501-b64a-5d738fb3cc64_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fa4db-7591-77dd-ac53-b5fe62f2f348" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fa4db-7591-7501-b64a-5d738fb3cc64" xlink:to="loc_srt_RangeMember_019fa4db-7591-77dd-ac53-b5fe62f2f348" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fa4db-7591-7866-974b-b8a1774ba14e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fa4db-7591-77dd-ac53-b5fe62f2f348" xlink:to="loc_srt_MinimumMember_019fa4db-7591-7866-974b-b8a1774ba14e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fa4db-7591-7ea7-abcf-bcc9582bce8d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fa4db-7591-77dd-ac53-b5fe62f2f348" xlink:to="loc_srt_MaximumMember_019fa4db-7591-7ea7-abcf-bcc9582bce8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019fa4db-7591-74e5-b03d-95e41a35fcf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:to="loc_us-gaap_NumberOfReportableSegments_019fa4db-7591-74e5-b03d-95e41a35fcf2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms_019fa4db-7591-78e1-8e1d-461986eaec46" xlink:href="moh-20260930.xsd#moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:to="loc_moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms_019fa4db-7591-78e1-8e1d-461986eaec46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms_019fa4db-7591-741b-b7b1-b128a0d6bb2c" xlink:href="moh-20260930.xsd#moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:to="loc_moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms_019fa4db-7591-741b-b7b1-b128a0d6bb2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_HealthPlanContractTerm_019fa4db-7591-7bfb-acc5-bf525fe0f2fb" xlink:href="moh-20260930.xsd#moh_HealthPlanContractTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019fa4db-7591-7d89-a304-51ec5c71605e" xlink:to="loc_moh_HealthPlanContractTerm_019fa4db-7591-7bfb-acc5-bf525fe0f2fb" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#SignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fa4db-7591-7385-9c78-7ac8c251b0dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fa4db-7591-7385-9c78-7ac8c251b0dc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019fa4db-7591-75cd-b4cb-5e4f198437bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fa4db-7591-7385-9c78-7ac8c251b0dc" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019fa4db-7591-75cd-b4cb-5e4f198437bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_019fa4db-7591-75cd-b4cb-5e4f198437bc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019fa4db-7591-75cd-b4cb-5e4f198437bc" xlink:to="loc_us-gaap_ReceivableTypeDomain_019fa4db-7591-75cd-b4cb-5e4f198437bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_019fa4db-7591-7d55-a8a1-55203af88c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019fa4db-7591-75cd-b4cb-5e4f198437bc" xlink:to="loc_us-gaap_ReceivableTypeDomain_019fa4db-7591-7d55-a8a1-55203af88c5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_GovernmentReceivablesMember_019fa4db-7591-7677-8b7c-cba3bce9ebbd" xlink:href="moh-20260930.xsd#moh_GovernmentReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_019fa4db-7591-7d55-a8a1-55203af88c5b" xlink:to="loc_moh_GovernmentReceivablesMember_019fa4db-7591-7677-8b7c-cba3bce9ebbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7591-7b73-8b36-9ed8be1a6e61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fa4db-7591-7385-9c78-7ac8c251b0dc" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7591-7b73-8b36-9ed8be1a6e61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7591-7b73-8b36-9ed8be1a6e61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7591-7b73-8b36-9ed8be1a6e61" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7591-7b73-8b36-9ed8be1a6e61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7591-7c55-a789-58d7ebfbbd73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7591-7b73-8b36-9ed8be1a6e61" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7591-7c55-a789-58d7ebfbbd73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_StructuredSecuritiesMember_019fa4db-7591-7ce8-9fa9-da4ab68e5789" xlink:href="moh-20260930.xsd#moh_StructuredSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7591-7c55-a789-58d7ebfbbd73" xlink:to="loc_moh_StructuredSecuritiesMember_019fa4db-7591-7ce8-9fa9-da4ab68e5789" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fa4db-7591-74e8-944f-952dc4fd258f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fa4db-7591-7385-9c78-7ac8c251b0dc" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fa4db-7591-74e8-944f-952dc4fd258f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-74e8-944f-952dc4fd258f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fa4db-7591-74e8-944f-952dc4fd258f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-74e8-944f-952dc4fd258f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-746c-8696-af6633d5c8a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fa4db-7591-74e8-944f-952dc4fd258f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-746c-8696-af6633d5c8a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ContractRightsAndLicensesMember_019fa4db-7591-7519-a510-1c3abc3394fd" xlink:href="moh-20260930.xsd#moh_ContractRightsAndLicensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-746c-8696-af6633d5c8a0" xlink:to="loc_moh_ContractRightsAndLicensesMember_019fa4db-7591-7519-a510-1c3abc3394fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ProviderNetworksMember_019fa4db-7591-73b9-8b0e-ba0e82d12720" xlink:href="moh-20260930.xsd#moh_ProviderNetworksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-746c-8696-af6633d5c8a0" xlink:to="loc_moh_ProviderNetworksMember_019fa4db-7591-73b9-8b0e-ba0e82d12720" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_019fa4db-7591-7c47-9192-d9669f86af10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fa4db-7591-746c-8696-af6633d5c8a0" xlink:to="loc_us-gaap_TradeNamesMember_019fa4db-7591-7c47-9192-d9669f86af10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_019fa4db-7591-7dfb-b8bc-cfdcc6038e61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_us-gaap_ReceivablesNetCurrent_019fa4db-7591-7dfb-b8bc-cfdcc6038e61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold_019fa4db-7591-7efd-b5ca-7bbf90831b9b" xlink:href="moh-20260930.xsd#moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold_019fa4db-7591-7efd-b5ca-7bbf90831b9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019fa4db-7591-77c3-a815-6cb45ff2caf1" xlink:href="moh-20260930.xsd#moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019fa4db-7591-77c3-a815-6cb45ff2caf1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019fa4db-7591-78db-918e-18fb78de3cdd" xlink:href="moh-20260930.xsd#moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019fa4db-7591-78db-918e-18fb78de3cdd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019fa4db-7591-710a-804d-63d7b170ce0e" xlink:href="moh-20260930.xsd#moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019fa4db-7591-710a-804d-63d7b170ce0e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019fa4db-7591-7f30-ac31-fe8b6553785b" xlink:href="moh-20260930.xsd#moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019fa4db-7591-7f30-ac31-fe8b6553785b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing_019fa4db-7591-7fd5-a872-204fccc559e7" xlink:href="moh-20260930.xsd#moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing_019fa4db-7591-7fd5-a872-204fccc559e7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable_019fa4db-7591-7598-bf4d-f8b1313c4f0f" xlink:href="moh-20260930.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable_019fa4db-7591-7598-bf4d-f8b1313c4f0f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable_019fa4db-7591-7d70-9e65-0ba6dfa2e3eb" xlink:href="moh-20260930.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable_019fa4db-7591-7d70-9e65-0ba6dfa2e3eb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable_019fa4db-7591-7537-a264-478b3884be04" xlink:href="moh-20260930.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable_019fa4db-7591-7537-a264-478b3884be04" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_InvestmentsMaturityPeriod_019fa4db-7591-77d2-9aae-b0e886e87b66" xlink:href="moh-20260930.xsd#moh_InvestmentsMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_InvestmentsMaturityPeriod_019fa4db-7591-77d2-9aae-b0e886e87b66" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_InvestmentsAverageMaturityPeriod_019fa4db-7591-7f79-b3a9-6c156840d074" xlink:href="moh-20260930.xsd#moh_InvestmentsAverageMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_moh_InvestmentsAverageMaturityPeriod_019fa4db-7591-7f79-b3a9-6c156840d074" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_019fa4db-7591-7e54-ba46-45013243d3fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fa4db-7591-7933-9a6d-7d5de1c79ed4" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_019fa4db-7591-7e54-ba46-45013243d3fa" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fa4db-7640-7ae3-bdc5-1dfd2a3c74ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fa4db-7591-7e69-be2d-5349683ec5ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fa4db-7640-7ae3-bdc5-1dfd2a3c74ab" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fa4db-7591-7e69-be2d-5349683ec5ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fa4db-7591-7cba-a57a-bdd3b95e4f10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fa4db-7591-7e69-be2d-5349683ec5ee" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fa4db-7591-7cba-a57a-bdd3b95e4f10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7cba-a57a-bdd3b95e4f10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fa4db-7591-7cba-a57a-bdd3b95e4f10" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7cba-a57a-bdd3b95e4f10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7389-9a2f-de646cfa6313" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fa4db-7591-7cba-a57a-bdd3b95e4f10" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7389-9a2f-de646cfa6313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019fa4db-7591-7b52-9204-7a691e89b8dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7389-9a2f-de646cfa6313" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019fa4db-7591-7b52-9204-7a691e89b8dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019fa4db-7591-75bf-bfb1-b11e3a6e4983" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7389-9a2f-de646cfa6313" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019fa4db-7591-75bf-bfb1-b11e3a6e4983" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019fa4db-7591-720d-9955-ab6f965c93db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fa4db-7591-7389-9a2f-de646cfa6313" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019fa4db-7591-720d-9955-ab6f965c93db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7b13-8d52-3d488a265b65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fa4db-7591-7e69-be2d-5349683ec5ee" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7b13-8d52-3d488a265b65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7b13-8d52-3d488a265b65_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7b13-8d52-3d488a265b65" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7b13-8d52-3d488a265b65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7b13-8d52-3d488a265b65" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-70a1-bd54-18e710b939cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-70a1-bd54-18e710b939cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_019fa4db-7640-729d-9708-a4b7d905a948" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_019fa4db-7640-729d-9708-a4b7d905a948" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-7188-90c4-486962e1ce3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-7188-90c4-486962e1ce3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryNotesSecuritiesMember_019fa4db-7640-7638-8178-70bbe28282fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USTreasuryNotesSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_us-gaap_USTreasuryNotesSecuritiesMember_019fa4db-7640-7638-8178-70bbe28282fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7a1a-bb26-dfbde813bc4b" xlink:href="moh-20260930.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7a1a-bb26-dfbde813bc4b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019fa4db-7640-7f62-919e-1193dc1cd4c5" xlink:href="moh-20260930.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7551-9b6b-75a2500b57b3" xlink:to="loc_moh_OtherSecuritiesMember_019fa4db-7640-7f62-919e-1193dc1cd4c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fa4db-7640-7ccb-b71d-dfc515d36549" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fa4db-7640-7ae3-bdc5-1dfd2a3c74ab" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fa4db-7640-7ccb-b71d-dfc515d36549" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019fa4db-7640-7209-af73-38a333e79c13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fa4db-7640-7ccb-b71d-dfc515d36549" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019fa4db-7640-7209-af73-38a333e79c13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019fa4db-7640-77ac-8cb6-d2be5e20fa49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fa4db-7640-7ccb-b71d-dfc515d36549" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019fa4db-7640-77ac-8cb6-d2be5e20fa49" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/FairValueMeasurementsLongTermDebtDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#FairValueMeasurementsLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/FairValueMeasurementsLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fa4db-7640-788e-b9ef-42c0e7020fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fa4db-7640-7a19-be8a-328cd62ac5bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fa4db-7640-788e-b9ef-42c0e7020fb1" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fa4db-7640-7a19-be8a-328cd62ac5bf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019fa4db-7640-7a96-b0ad-d122c41a595c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fa4db-7640-7a19-be8a-328cd62ac5bf" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019fa4db-7640-7a96-b0ad-d122c41a595c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7a96-b0ad-d122c41a595c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019fa4db-7640-7a96-b0ad-d122c41a595c" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7a96-b0ad-d122c41a595c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fa4db-7640-786e-a567-eadded1665bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019fa4db-7640-7a96-b0ad-d122c41a595c" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fa4db-7640-786e-a567-eadded1665bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7d5a-b5f3-cf9d7196b1a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fa4db-7640-786e-a567-eadded1665bc" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7d5a-b5f3-cf9d7196b1a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019fa4db-7640-7ae3-96ec-8ef4c93e8230" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7d5a-b5f3-cf9d7196b1a8" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019fa4db-7640-7ae3-96ec-8ef4c93e8230" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019fa4db-7640-7a04-a481-7bdacfbf7ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fa4db-7640-7d5a-b5f3-cf9d7196b1a8" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019fa4db-7640-7a04-a481-7bdacfbf7ff3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7b8e-a7f8-2971cbf382b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fa4db-7640-7a19-be8a-328cd62ac5bf" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7b8e-a7f8-2971cbf382b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7b8e-a7f8-2971cbf382b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7b8e-a7f8-2971cbf382b6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7b8e-a7f8-2971cbf382b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7e16-9b18-6481eb59ae44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7b8e-a7f8-2971cbf382b6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7e16-9b18-6481eb59ae44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019fa4db-7640-7dc6-b21d-3361e9c0609f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7e16-9b18-6481eb59ae44" xlink:to="loc_us-gaap_SeniorNotesMember_019fa4db-7640-7dc6-b21d-3361e9c0609f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7412-967e-d2348b13d9ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fa4db-7640-7a19-be8a-328cd62ac5bf" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7412-967e-d2348b13d9ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7412-967e-d2348b13d9ec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7412-967e-d2348b13d9ec" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7412-967e-d2348b13d9ec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7412-967e-d2348b13d9ec" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A4.375SeniorNotesDue2028Member_019fa4db-7640-75a4-aefd-7750106bcbdf" xlink:href="moh-20260930.xsd#moh_A4.375SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:to="loc_moh_A4.375SeniorNotesDue2028Member_019fa4db-7640-75a4-aefd-7750106bcbdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2030Member_019fa4db-7640-79a5-9d55-8ade8966aea2" xlink:href="moh-20260930.xsd#moh_A3.875SeniorNotesDue2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:to="loc_moh_A3.875SeniorNotesDue2030Member_019fa4db-7640-79a5-9d55-8ade8966aea2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.500SeniorNotesDue2031Member_019fa4db-7640-7536-aa21-1aae9b87c77c" xlink:href="moh-20260930.xsd#moh_A6.500SeniorNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:to="loc_moh_A6.500SeniorNotesDue2031Member_019fa4db-7640-7536-aa21-1aae9b87c77c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2032Member_019fa4db-7640-71f6-aa17-93993f9a0d03" xlink:href="moh-20260930.xsd#moh_A3.875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:to="loc_moh_A3.875SeniorNotesDue2032Member_019fa4db-7640-71f6-aa17-93993f9a0d03" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.250SeniorNotesDue2033Member_019fa4db-7640-7c4c-b59b-68270da6c187" xlink:href="moh-20260930.xsd#moh_A6.250SeniorNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7172-bbc9-2ebf23967262" xlink:to="loc_moh_A6.250SeniorNotesDue2033Member_019fa4db-7640-7c4c-b59b-68270da6c187" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fa4db-7640-74f2-91ae-1a4976ef63e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fa4db-7640-788e-b9ef-42c0e7020fb1" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fa4db-7640-74f2-91ae-1a4976ef63e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019fa4db-7640-7ecf-9599-698e03e98ac3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fa4db-7640-788e-b9ef-42c0e7020fb1" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019fa4db-7640-7ecf-9599-698e03e98ac3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/InvestmentsScheduleofInvestmentsDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#InvestmentsScheduleofInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/InvestmentsScheduleofInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-7d09-9f36-1ecaf7bea95f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-7d09-9f36-1ecaf7bea95f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7a1b-9111-a301057b29f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-7d09-9f36-1ecaf7bea95f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7a1b-9111-a301057b29f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7a1b-9111-a301057b29f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7a1b-9111-a301057b29f1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7a1b-9111-a301057b29f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-7a1b-9111-a301057b29f1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-777a-a73c-99fee2a15268" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-777a-a73c-99fee2a15268" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_019fa4db-7640-794f-8c1d-a008f783be98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_019fa4db-7640-794f-8c1d-a008f783be98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-720b-9d8f-f7daea9e0415" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-720b-9d8f-f7daea9e0415" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryNotesSecuritiesMember_019fa4db-7640-7d77-a7cb-3f8ebd037ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USTreasuryNotesSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_us-gaap_USTreasuryNotesSecuritiesMember_019fa4db-7640-7d77-a7cb-3f8ebd037ba0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7cc3-a79b-83022dd4ef59" xlink:href="moh-20260930.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7cc3-a79b-83022dd4ef59" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019fa4db-7640-7275-ba4c-7465bca55d02" xlink:href="moh-20260930.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-746e-86d3-103486c9031a" xlink:to="loc_moh_OtherSecuritiesMember_019fa4db-7640-7275-ba4c-7465bca55d02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_019fa4db-7640-7fc0-abd5-80481367ca53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_019fa4db-7640-7fc0-abd5-80481367ca53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fa4db-7640-7e1f-96a6-ab8c2ae84fac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fa4db-7640-7e1f-96a6-ab8c2ae84fac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fa4db-7640-7d6f-ad72-9f0bbabb3ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fa4db-7640-7d6f-ad72-9f0bbabb3ac4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019fa4db-7640-7742-aa20-726e06ed8363" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-7d9a-8b41-5fb08361c930" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019fa4db-7640-7742-aa20-726e06ed8363" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#InvestmentsAvailableforSaleInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-778a-8ab0-ea404b5069a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-778a-8ab0-ea404b5069a4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-77f5-828f-3b1b5763adb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fa4db-7640-778a-8ab0-ea404b5069a4" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-77f5-828f-3b1b5763adb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-77f5-828f-3b1b5763adb3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-77f5-828f-3b1b5763adb3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-77f5-828f-3b1b5763adb3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fa4db-7640-77f5-828f-3b1b5763adb3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-78c4-befe-50dfc5c84e1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019fa4db-7640-78c4-befe-50dfc5c84e1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_019fa4db-7640-7903-9f34-bcdcbde9d547" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_019fa4db-7640-7903-9f34-bcdcbde9d547" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-7b70-945e-72a9d0d293a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019fa4db-7640-7b70-945e-72a9d0d293a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7825-9dbf-53303400cced" xlink:href="moh-20260930.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:to="loc_moh_MunicipalSecuritiesMember_019fa4db-7640-7825-9dbf-53303400cced" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019fa4db-7640-775c-93b6-92ab0dfb83e8" xlink:href="moh-20260930.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fa4db-7640-7ee8-9663-3cca04202699" xlink:to="loc_moh_OtherSecuritiesMember_019fa4db-7640-775c-93b6-92ab0dfb83e8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019fa4db-7640-7865-b0e8-796df3fda256" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019fa4db-7640-7865-b0e8-796df3fda256" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019fa4db-7640-7d40-9583-8d0f1fe5c96f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019fa4db-7640-7d40-9583-8d0f1fe5c96f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019fa4db-7640-7efc-807e-e56b0e0cf2a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019fa4db-7640-7efc-807e-e56b0e0cf2a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019fa4db-7640-7d18-969e-b4d64c6515d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019fa4db-7640-7d18-969e-b4d64c6515d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019fa4db-7640-7e68-8057-ace3c96ff081" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019fa4db-7640-7e68-8057-ace3c96ff081" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019fa4db-7640-7fa6-82a0-d64a145c06ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fa4db-7640-77fc-a239-321e15191f2e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019fa4db-7640-7fa6-82a0-d64a145c06ee" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019fa4db-7640-7e27-bef6-0a1837412ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019fa4db-7640-7f05-bd41-dc4eeb3b3b50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019fa4db-7640-7e27-bef6-0a1837412ecf" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019fa4db-7640-7f05-bd41-dc4eeb3b3b50" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-73b7-9b7f-83e6d7a46fbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019fa4db-7640-7f05-bd41-dc4eeb3b3b50" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-73b7-9b7f-83e6d7a46fbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7640-73b7-9b7f-83e6d7a46fbb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-73b7-9b7f-83e6d7a46fbb" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7640-73b7-9b7f-83e6d7a46fbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-73b7-9b7f-83e6d7a46fbb" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019fa4db-7640-7639-8d7e-d3da02fe8f29" xlink:href="moh-20260930.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:to="loc_moh_MedicaidMember_019fa4db-7640-7639-8d7e-d3da02fe8f29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019fa4db-7640-7ec9-88a8-c8c2133800d8" xlink:href="moh-20260930.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:to="loc_moh_MedicareMember_019fa4db-7640-7ec9-88a8-c8c2133800d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MarketplaceMember_019fa4db-7640-7b23-a90b-e0e95b333c3d" xlink:href="moh-20260930.xsd#moh_MarketplaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:to="loc_moh_MarketplaceMember_019fa4db-7640-7b23-a90b-e0e95b333c3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherProgramMember_019fa4db-7640-79b6-8ec2-4222ba1a192f" xlink:href="moh-20260930.xsd#moh_OtherProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-70e8-a8fe-d8da49dddd14" xlink:to="loc_moh_OtherProgramMember_019fa4db-7640-79b6-8ec2-4222ba1a192f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019fa4db-7640-7e27-bef6-0a1837412ecf" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019fa4db-7640-7cd3-9ed3-ca5bac2dd34f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019fa4db-7640-7cd3-9ed3-ca5bac2dd34f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ComponentsOfMedicalCareCostsAbstract_019fa4db-7640-793c-80c9-b4ee583efdae" xlink:href="moh-20260930.xsd#moh_ComponentsOfMedicalCareCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:to="loc_moh_ComponentsOfMedicalCareCostsAbstract_019fa4db-7640-793c-80c9-b4ee583efdae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019fa4db-7640-7238-9cf4-f502d0835662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019fa4db-7640-793c-80c9-b4ee583efdae" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019fa4db-7640-7238-9cf4-f502d0835662" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019fa4db-7640-75d5-8f69-276483c8d8ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019fa4db-7640-793c-80c9-b4ee583efdae" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019fa4db-7640-75d5-8f69-276483c8d8ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019fa4db-7640-7d47-add6-d79d371d9714" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019fa4db-7640-793c-80c9-b4ee583efdae" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019fa4db-7640-7d47-add6-d79d371d9714" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PaymentsForMedicalCareCostsAbstract_019fa4db-7640-769f-8472-416143a14266" xlink:href="moh-20260930.xsd#moh_PaymentsForMedicalCareCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:to="loc_moh_PaymentsForMedicalCareCostsAbstract_019fa4db-7640-769f-8472-416143a14266" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019fa4db-7640-716b-a588-f0c36fdb1502" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019fa4db-7640-769f-8472-416143a14266" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019fa4db-7640-716b-a588-f0c36fdb1502" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019fa4db-7640-7a34-b2ff-1fc008bf5d26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019fa4db-7640-769f-8472-416143a14266" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019fa4db-7640-7a34-b2ff-1fc008bf5d26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019fa4db-7640-79ec-92fa-55fc0d13a542" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLossesAndLossAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019fa4db-7640-769f-8472-416143a14266" xlink:to="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019fa4db-7640-79ec-92fa-55fc0d13a542" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments_019fa4db-7640-704a-9c17-6105437be4b0" xlink:href="moh-20260930.xsd#moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:to="loc_moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments_019fa4db-7640-704a-9c17-6105437be4b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider_019fa4db-7640-7903-a4d5-17b9e4745aad" xlink:href="moh-20260930.xsd#moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019fa4db-7640-78bd-bf4e-23866d43b653" xlink:to="loc_moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider_019fa4db-7640-7903-a4d5-17b9e4745aad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019fa4db-7640-721b-b5d1-3a198ebc91fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#DebtScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-75c2-9feb-4e181276c2f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:to="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-75c2-9feb-4e181276c2f7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7da1-8cd7-f908fffcc6ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-75c2-9feb-4e181276c2f7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7da1-8cd7-f908fffcc6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7da1-8cd7-f908fffcc6ec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7da1-8cd7-f908fffcc6ec" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7da1-8cd7-f908fffcc6ec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7cf4-a438-fc5fa48a2e0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7da1-8cd7-f908fffcc6ec" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7cf4-a438-fc5fa48a2e0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019fa4db-7640-7caf-adc8-5d8851c7cd63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7cf4-a438-fc5fa48a2e0e" xlink:to="loc_us-gaap_SeniorNotesMember_019fa4db-7640-7caf-adc8-5d8851c7cd63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7ef0-996c-27c0d47cfb20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-75c2-9feb-4e181276c2f7" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7ef0-996c-27c0d47cfb20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7ef0-996c-27c0d47cfb20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7ef0-996c-27c0d47cfb20" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7ef0-996c-27c0d47cfb20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7ef0-996c-27c0d47cfb20" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A4.375SeniorNotesDue2028Member_019fa4db-7640-791b-ac5c-dc86252d0644" xlink:href="moh-20260930.xsd#moh_A4.375SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:to="loc_moh_A4.375SeniorNotesDue2028Member_019fa4db-7640-791b-ac5c-dc86252d0644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2030Member_019fa4db-7640-788f-800e-420dd2cf7f57" xlink:href="moh-20260930.xsd#moh_A3.875SeniorNotesDue2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:to="loc_moh_A3.875SeniorNotesDue2030Member_019fa4db-7640-788f-800e-420dd2cf7f57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.500SeniorNotesDue2031Member_019fa4db-7640-7dcb-9ba2-03699fad856f" xlink:href="moh-20260930.xsd#moh_A6.500SeniorNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:to="loc_moh_A6.500SeniorNotesDue2031Member_019fa4db-7640-7dcb-9ba2-03699fad856f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2032Member_019fa4db-7640-7de7-a119-0807313f09e5" xlink:href="moh-20260930.xsd#moh_A3.875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:to="loc_moh_A3.875SeniorNotesDue2032Member_019fa4db-7640-7de7-a119-0807313f09e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.250SeniorNotesDue2033Member_019fa4db-7640-74b1-8174-c1a84509292d" xlink:href="moh-20260930.xsd#moh_A6.250SeniorNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-70c4-9e9c-91e9a0a19c2a" xlink:to="loc_moh_A6.250SeniorNotesDue2033Member_019fa4db-7640-74b1-8174-c1a84509292d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fa4db-7640-7316-b033-67d5005888e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fa4db-7640-7316-b033-67d5005888e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount_019fa4db-7640-7556-9750-fc96d966eae4" xlink:href="moh-20260930.xsd#moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:to="loc_moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount_019fa4db-7640-7556-9750-fc96d966eae4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019fa4db-7640-734e-9cb3-f633a6f5f468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019fa4db-7640-734e-9cb3-f633a6f5f468" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019fa4db-7640-7a0b-a767-75fea24431b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-7599-be38-e19b3ad887b9" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019fa4db-7640-7a0b-a767-75fea24431b4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:to="loc_us-gaap_CreditFacilityAxis_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a" xlink:to="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7137-b98e-4862958829db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019fa4db-7640-7bf8-8e46-ce4ffaa2da8a" xlink:to="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7137-b98e-4862958829db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019fa4db-7640-763c-9df6-fba22410aa32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7137-b98e-4862958829db" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019fa4db-7640-763c-9df6-fba22410aa32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_SwinglineSubFacilityMember_019fa4db-7640-7cd4-95b9-a81829950bb5" xlink:href="moh-20260930.xsd#moh_SwinglineSubFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7137-b98e-4862958829db" xlink:to="loc_moh_SwinglineSubFacilityMember_019fa4db-7640-7cd4-95b9-a81829950bb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LetterOfCreditSubFacilityMember_019fa4db-7640-7bed-b808-985b301d2663" xlink:href="moh-20260930.xsd#moh_LetterOfCreditSubFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fa4db-7640-7137-b98e-4862958829db" xlink:to="loc_moh_LetterOfCreditSubFacilityMember_019fa4db-7640-7bed-b808-985b301d2663" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7bf0-ad2f-4f53bf457ec8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7bf0-ad2f-4f53bf457ec8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7bf0-ad2f-4f53bf457ec8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7bf0-ad2f-4f53bf457ec8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7bf0-ad2f-4f53bf457ec8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7b52-a7e4-12086fa48f12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fa4db-7640-7bf0-ad2f-4f53bf457ec8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7b52-a7e4-12086fa48f12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NewCreditAgreementMember_019fa4db-7640-764a-a65c-42ad33dcc511" xlink:href="moh-20260930.xsd#moh_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7b52-a7e4-12086fa48f12" xlink:to="loc_moh_NewCreditAgreementMember_019fa4db-7640-764a-a65c-42ad33dcc511" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_TermLoanMember_019fa4db-7640-7a7a-a916-f7cfe3254b1a" xlink:href="moh-20260930.xsd#moh_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fa4db-7640-7b52-a7e4-12086fa48f12" xlink:to="loc_moh_TermLoanMember_019fa4db-7640-7a7a-a916-f7cfe3254b1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7650-948b-1a7a4bd75c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7650-948b-1a7a4bd75c5b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7650-948b-1a7a4bd75c5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7650-948b-1a7a4bd75c5b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7650-948b-1a7a4bd75c5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7451-8e17-f654629d7a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fa4db-7640-7650-948b-1a7a4bd75c5b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7451-8e17-f654629d7a4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019fa4db-7640-7c7c-9764-d3b4e359efad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7451-8e17-f654629d7a4f" xlink:to="loc_us-gaap_LineOfCreditMember_019fa4db-7640-7c7c-9764-d3b4e359efad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DelayedDrawTermLoanMember_019fa4db-7640-75ac-9e59-4ab5df331ded" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fa4db-7640-7451-8e17-f654629d7a4f" xlink:to="loc_us-gaap_DelayedDrawTermLoanMember_019fa4db-7640-75ac-9e59-4ab5df331ded" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fa4db-7640-7a83-9e7c-273c06c3ed5c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:to="loc_srt_RangeAxis_019fa4db-7640-7a83-9e7c-273c06c3ed5c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fa4db-7640-7a83-9e7c-273c06c3ed5c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fa4db-7640-7a83-9e7c-273c06c3ed5c" xlink:to="loc_srt_RangeMember_019fa4db-7640-7a83-9e7c-273c06c3ed5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fa4db-7640-7b11-95a4-7fa1f29206e2" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fa4db-7640-7a83-9e7c-273c06c3ed5c" xlink:to="loc_srt_RangeMember_019fa4db-7640-7b11-95a4-7fa1f29206e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fa4db-7640-704d-8295-3fa487351258" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fa4db-7640-7b11-95a4-7fa1f29206e2" xlink:to="loc_srt_MinimumMember_019fa4db-7640-704d-8295-3fa487351258" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fa4db-7640-767d-8bb6-9ea1750fbc54" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fa4db-7640-7b11-95a4-7fa1f29206e2" xlink:to="loc_srt_MaximumMember_019fa4db-7640-767d-8bb6-9ea1750fbc54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodAxis_019fa4db-7640-7912-a9cf-fd3629c74d68" xlink:href="moh-20260930.xsd#moh_DebtInstrumentCovenantPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fa4db-7640-76aa-b455-2e6fc70a6de4" xlink:to="loc_moh_DebtInstrumentCovenantPeriodAxis_019fa4db-7640-7912-a9cf-fd3629c74d68" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-7912-a9cf-fd3629c74d68_default" xlink:href="moh-20260930.xsd#moh_DebtInstrumentCovenantPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_moh_DebtInstrumentCovenantPeriodAxis_019fa4db-7640-7912-a9cf-fd3629c74d68" xlink:to="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-7912-a9cf-fd3629c74d68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:href="moh-20260930.xsd#moh_DebtInstrumentCovenantPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_moh_DebtInstrumentCovenantPeriodAxis_019fa4db-7640-7912-a9cf-fd3629c74d68" xlink:to="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodOneMember_019fa4db-7640-7744-9c2f-a485dacf58e6" xlink:href="moh-20260930.xsd#moh_CovenantPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:to="loc_moh_CovenantPeriodOneMember_019fa4db-7640-7744-9c2f-a485dacf58e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodTwoMember_019fa4db-7640-7b2d-801b-5b30ec309cd1" xlink:href="moh-20260930.xsd#moh_CovenantPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:to="loc_moh_CovenantPeriodTwoMember_019fa4db-7640-7b2d-801b-5b30ec309cd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodThreeMember_019fa4db-7640-7c13-927e-c6406cc92c0a" xlink:href="moh-20260930.xsd#moh_CovenantPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:to="loc_moh_CovenantPeriodThreeMember_019fa4db-7640-7c13-927e-c6406cc92c0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodFourMember_019fa4db-7640-7190-b2c2-70e444bf90b9" xlink:href="moh-20260930.xsd#moh_CovenantPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019fa4db-7640-77d1-b67c-c9b570e8d5f0" xlink:to="loc_moh_CovenantPeriodFourMember_019fa4db-7640-7190-b2c2-70e444bf90b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019fa4db-7640-786e-aba3-40f3680b499a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_us-gaap_LineOfCredit_019fa4db-7640-786e-aba3-40f3680b499a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019fa4db-7640-71ad-8658-b89caada3315" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019fa4db-7640-71ad-8658-b89caada3315" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019fa4db-7640-7a59-82d4-e723c92274b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019fa4db-7640-7a59-82d4-e723c92274b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019fa4db-7640-7702-91f0-d111c5c20ba3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_us-gaap_DebtInstrumentTerm_019fa4db-7640-7702-91f0-d111c5c20ba3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantInterestCoverageRatioMinimum_019fa4db-7640-77ce-aa88-cb840d5eca97" xlink:href="moh-20260930.xsd#moh_DebtInstrumentCovenantInterestCoverageRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_moh_DebtInstrumentCovenantInterestCoverageRatioMinimum_019fa4db-7640-77ce-aa88-cb840d5eca97" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentDebtToCapitalizationRatio_019fa4db-7640-76d6-bcd0-737f070caf43" xlink:href="moh-20260930.xsd#moh_DebtInstrumentDebtToCapitalizationRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_moh_DebtInstrumentDebtToCapitalizationRatio_019fa4db-7640-76d6-bcd0-737f070caf43" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount_019fa4db-7640-7c76-ba1b-2199141b8380" xlink:href="moh-20260930.xsd#moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fa4db-7640-73bc-bba2-dd883f179fde" xlink:to="loc_moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount_019fa4db-7640-7c76-ba1b-2199141b8380" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails" xlink:type="simple" xlink:href="moh-20260930.xsd#SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fa4db-7640-7b47-8676-700ee2b1ae4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fa4db-7640-7b47-8676-700ee2b1ae4f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019fa4db-7640-7ebb-b8c8-c428cc6af6fd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fa4db-7640-7b47-8676-700ee2b1ae4f" xlink:to="loc_srt_ConsolidationItemsAxis_019fa4db-7640-7ebb-b8c8-c428cc6af6fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019fa4db-7640-7ebb-b8c8-c428cc6af6fd_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019fa4db-7640-7ebb-b8c8-c428cc6af6fd" xlink:to="loc_srt_ConsolidationItemsDomain_019fa4db-7640-7ebb-b8c8-c428cc6af6fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019fa4db-7640-7a04-91d2-f542539b3639" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019fa4db-7640-7ebb-b8c8-c428cc6af6fd" xlink:to="loc_srt_ConsolidationItemsDomain_019fa4db-7640-7a04-91d2-f542539b3639" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019fa4db-7640-72d0-9b27-677912e3740a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019fa4db-7640-7a04-91d2-f542539b3639" xlink:to="loc_us-gaap_OperatingSegmentsMember_019fa4db-7640-72d0-9b27-677912e3740a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-71b1-9d37-1dc39d55a337" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fa4db-7640-7b47-8676-700ee2b1ae4f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-71b1-9d37-1dc39d55a337" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7640-71b1-9d37-1dc39d55a337_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-71b1-9d37-1dc39d55a337" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7640-71b1-9d37-1dc39d55a337_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fa4db-7640-71b1-9d37-1dc39d55a337" xlink:to="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019fa4db-7640-7401-a26d-000fef2875a7" xlink:href="moh-20260930.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:to="loc_moh_MedicaidMember_019fa4db-7640-7401-a26d-000fef2875a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019fa4db-7640-70b8-ba87-4733bcb49efc" xlink:href="moh-20260930.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:to="loc_moh_MedicareMember_019fa4db-7640-70b8-ba87-4733bcb49efc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MarketplaceMember_019fa4db-7640-7e01-9014-8f80588a213a" xlink:href="moh-20260930.xsd#moh_MarketplaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:to="loc_moh_MarketplaceMember_019fa4db-7640-7e01-9014-8f80588a213a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherProgramMember_019fa4db-7640-728f-b709-fbbb7c31b216" xlink:href="moh-20260930.xsd#moh_OtherProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fa4db-7640-7155-affd-786eb3330b5e" xlink:to="loc_moh_OtherProgramMember_019fa4db-7640-728f-b709-fbbb7c31b216" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fa4db-7640-73df-b0e4-f2f02eb4c58a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fa4db-7640-7b47-8676-700ee2b1ae4f" xlink:to="loc_srt_ProductOrServiceAxis_019fa4db-7640-73df-b0e4-f2f02eb4c58a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fa4db-7640-73df-b0e4-f2f02eb4c58a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fa4db-7640-73df-b0e4-f2f02eb4c58a" xlink:to="loc_srt_ProductsAndServicesDomain_019fa4db-7640-73df-b0e4-f2f02eb4c58a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fa4db-7640-7c47-a79b-4f1716fabbc4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fa4db-7640-73df-b0e4-f2f02eb4c58a" xlink:to="loc_srt_ProductsAndServicesDomain_019fa4db-7640-7c47-a79b-4f1716fabbc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalMember_019fa4db-7640-709d-a44e-8878d13def40" xlink:href="moh-20260930.xsd#moh_MedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fa4db-7640-7c47-a79b-4f1716fabbc4" xlink:to="loc_moh_MedicalMember_019fa4db-7640-709d-a44e-8878d13def40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_019fa4db-7640-7270-a807-148e76dfce03" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fa4db-7640-7c47-a79b-4f1716fabbc4" xlink:to="loc_us-gaap_ServiceMember_019fa4db-7640-7270-a807-148e76dfce03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019fa4db-7640-7ffe-b300-ab23f0abf7d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_RevenuesAbstract_019fa4db-7640-7ffe-b300-ab23f0abf7d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_019fa4db-7640-7231-bc97-27e33ea63a59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019fa4db-7640-7ffe-b300-ab23f0abf7d6" xlink:to="loc_us-gaap_PremiumsEarnedNet_019fa4db-7640-7231-bc97-27e33ea63a59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ServiceRevenue_019fa4db-7640-79eb-a132-483f929c72b2" xlink:href="moh-20260930.xsd#moh_ServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019fa4db-7640-7ffe-b300-ab23f0abf7d6" xlink:to="loc_moh_ServiceRevenue_019fa4db-7640-79eb-a132-483f929c72b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PremiumsEarnedAndServiceRevenue_019fa4db-7640-7670-afe4-1602c8d62fc6" xlink:href="moh-20260930.xsd#moh_PremiumsEarnedAndServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_moh_PremiumsEarnedAndServiceRevenue_019fa4db-7640-7670-afe4-1602c8d62fc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncome_019fa4db-7640-7a6b-9047-171b103dbed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherOperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_OtherOperatingIncome_019fa4db-7640-7a6b-9047-171b103dbed8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019fa4db-7640-7f73-8f42-33e60a00e87b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_Revenues_019fa4db-7640-7f73-8f42-33e60a00e87b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_019fa4db-7640-76ac-9f9f-728ebbbc5cbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_019fa4db-7640-76ac-9f9f-728ebbbc5cbe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019fa4db-7640-7ca9-94e6-cec9f7ff5b43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019fa4db-7640-76ac-9f9f-728ebbbc5cbe" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019fa4db-7640-7ca9-94e6-cec9f7ff5b43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CostOfServiceRevenue_019fa4db-7640-7457-929e-fe4be7290169" xlink:href="moh-20260930.xsd#moh_CostOfServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019fa4db-7640-76ac-9f9f-728ebbbc5cbe" xlink:to="loc_moh_CostOfServiceRevenue_019fa4db-7640-7457-929e-fe4be7290169" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_SegmentExpenses_019fa4db-7640-7c33-b828-e48b8d722606" xlink:href="moh-20260930.xsd#moh_SegmentExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_moh_SegmentExpenses_019fa4db-7640-7c33-b828-e48b8d722606" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_019fa4db-7640-7af3-858e-13a1632fb1b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_OtherExpenses_019fa4db-7640-7af3-858e-13a1632fb1b0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019fa4db-7640-7b8d-bb55-a09233d2f349" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_OperatingIncomeLoss_019fa4db-7640-7b8d-bb55-a09233d2f349" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019fa4db-7640-719f-bac9-9da6b70bb164" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019fa4db-7640-719f-bac9-9da6b70bb164" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019fa4db-7640-76d0-baad-b42fcc32b64d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019fa4db-7640-76d0-baad-b42fcc32b64d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019fa4db-7640-7361-935e-56547ca72379" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fa4db-7640-7699-a7a0-797c9f0b1818" xlink:to="loc_us-gaap_GrossProfit_019fa4db-7640-7361-935e-56547ca72379" xlink:type="arc" order="10"/>
  </link:definitionLink>
</link:linkbase>
