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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2016-12-14</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000075208</issuerCik>
        <issuerName>OVERSEAS SHIPHOLDING GROUP INC</issuerName>
        <issuerTradingSymbol>OSG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001693233</rptOwnerCik>
            <rptOwnerName>O'Halloran Patrick Joseph</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>302 KNIGHTS RUN AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1200</rptOwnerStreet2>
            <rptOwnerCity>TAMPA</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33602</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP &amp; Chief Operations Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1726</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4513</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These restricted stock units were granted pursuant to the Overseas Shipholding Group, Inc. (&quot;OSG&quot;) Management Incentive Compensation Plan (the &quot;Plan&quot;) and vest as to one-half of such units on December 19, 2016 and one-half units on December 19, 2017.  Each unit represents the right to acquire one share of Class A Common Stock.  Settlement of vested units may be in either shares of Class A Common Stock or cash as determined by the Compensation and Human Resources Committee of the Board in its discretion.  Settlement must occur no later than March 15 of the calendar year following vesting of the units.</footnote>
        <footnote id="F2">The number of RSUs reported is based on the number of RSUs Mr. O'Halloran held as of immediately prior to the transaction pursuant to which International Seaways, Inc. was spun-off from the Registrant, and will be adjusted pursuant to the provisions of the Employee Matters Agreement entered into by and between International Seaways, Inc. and the Registrant and which adjustment, as of the date of filing, could not yet be calculated.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Susan Allan, Attorney-in-Fact, pursuant to a power of attorney attached hereto</signatureName>
        <signatureDate>2016-12-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
