<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-09-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000076282</issuerCik>
        <issuerName>PARK OHIO HOLDINGS CORP</issuerName>
        <issuerTradingSymbol>PKOH</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001210284</rptOwnerCik>
            <rptOwnerName>VILSACK ROBERT D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>6065 PARKLAND BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44124</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Secretary &amp; CLO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>1</aff10b5One>

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                </transactionShares>
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                </transactionAcquiredDisposedCode>
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                </transactionShares>
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                </transactionPricePerShare>
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                    <value>194</value>
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            <securityTitle>
                <value>Common Stock</value>
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                <value>2026-09-30</value>
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                <transactionCode>S</transactionCode>
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                <transactionShares>
                    <value>204</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47</value>
                </transactionPricePerShare>
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                    <value>D</value>
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        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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                    <value>47.07</value>
                </transactionPricePerShare>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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            <ownershipNature>
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    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks>Sales were made pursuant to a Rule 10b5-1 plan adopted on June 29, 2026.</remarks>

    <ownerSignature>
        <signatureName>Patrick W. Fogarty, Attorney-In-Fact for Robert D. Vilsack</signatureName>
        <signatureDate>2026-10-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
