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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-12-31</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001281774</issuerCik>
        <issuerName>TOWN SPORTS INTERNATIONAL HOLDINGS INC</issuerName>
        <issuerTradingSymbol>CLUB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001453077</rptOwnerCik>
            <rptOwnerName>Hirsch Daniel J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FARALLON CAPITAL MANAGEMENT, L.L.C.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE MARITIME PLAZA, SUITE 2100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Member of Group Owning 10%</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Daniel J. Hirsch (&quot;Hirsch&quot;) previously filed Form 3s and Form 4s with respect to securities of the Issuer owned directly by Farallon Capital Partners, L.P., Farallon Capital Institutional Partners, L.P., Farallon Capital Institutional Partners II, L.P., Farallon Capital Institutional Partners III, L.P. and Farallon Capital Offshore Investors II, L.P. (collectively, the &quot;Farallon Funds&quot;).</footnote>
        <footnote id="F2">As a managing member of Farallon Partners, L.L.C. (&quot;FPLLC&quot;), the general partner of each of the Farallon Funds, Hirsch may have been deemed a beneficial owner of the Issuer's securities deemed beneficially owned by FPLLC. Effective as of December 31, 2016, in connection with his resignation as managing member of FPLLC, Hirsch may no longer be deemed a beneficial owner of any of the Issuer's securities deemed beneficially owned by FPLLC.</footnote>
        <footnote id="F3">Hirsch and the other individuals identified in the prior Form 3s and Form 4s filed by the foregoing disclaims any beneficial ownership of any of the Issuer's securities reported or referred to herein or therein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the &quot;'34 Act&quot;), or otherwise, except to the extent of his or her pecuniary interest, if any. FPLLC disclaims any beneficial ownership of any of the Issuer's securities reported or referred to herein or in such prior Form 3s and Form 4s for purposes of Section 16 of the '34 Act or otherwise, except as to securities representing FPLLC's pro rata interest in, and interest in the profits of, the Farallon Funds.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Monica R. Landry, as attorney-in-fact and/or authorized signer for Daniel J. Hirsch</signatureName>
        <signatureDate>2017-01-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
