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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-02-05</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001062449</issuerCik>
        <issuerName>BUFFALO WILD WINGS INC</issuerName>
        <issuerTradingSymbol>BWLD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001541996</rptOwnerCik>
            <rptOwnerName>MARCATO CAPITAL MANAGEMENT LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FOUR EMBARCADERO CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001502803</rptOwnerCik>
            <rptOwnerName>Marcato International Master Fund, Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FOUR EMBARCADERO CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001618174</rptOwnerCik>
            <rptOwnerName>Marcato Special Opportunities Master Fund LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FOUR EMBARCADERO CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001558320</rptOwnerCik>
            <rptOwnerName>McGuire Richard</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FOUR EMBARCADERO CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>699</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>157</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>41700</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>41700</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>157.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Effective February 5, 2018, pursuant to that certain Agreement and Plan of Merger, dated as of November 27, 2017, by and among Arby's Restaurant Group, Inc., a Delaware corporation (&quot;Parent&quot;), IB Merger Sub I Corporation, a Minnesota corporation and a subsidiary of Parent (&quot;Merger Sub&quot;) and Buffalo Wild Wings, Inc., a Minnesota corporation (the &quot;Issuer&quot;), Merger Sub merged with and into the Issuer, with the Issuer continuing as the surviving corporation and as a wholly owned subsidiary of Parent (the &quot;Merger&quot;). As consideration for the Merger, the shares of common stock of the Issuer held by the Reporting Persons were automatically cancelled and converted into the right to receive $157.00 per share in cash.</footnote>
        <footnote id="F2">This Form 4 is being filed jointly by Marcato Capital Management, LP, a Delaware limited partnership (&quot;Marcato&quot;), Marcato International Master Fund, Ltd., a Cayman Islands exempted company (&quot;Marcato International&quot;), Marcato Special Opportunities Master Fund LP, a Cayman Islands limited partnership (&quot;Marcato Special Opportunities Fund&quot;), and Richard McGuire III, a citizen of the United States of America (collectively, the &quot;Reporting Persons&quot;), each of whom has the same business address as Marcato and may be deemed to have a pecuniary interest in securities reported on this Form 4 (the &quot;Subject Securities&quot;).</footnote>
        <footnote id="F3">Marcato, as the investment manager of Marcato International and Marcato Special Opportunities Fund, may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934. By virtue of Mr. McGuire's position as Managing Partner of Marcato, Mr. McGuire may be deemed to be the beneficial owner of the Subject Securities for purposes of Rule 16a-1(a) and Marcato, Marcato International and Marcato Special Opportunities Fund may be deemed to be the beneficial owner of the Subject Securities held by Mr. McGuire. Each of the Reporting Persons disclaims any beneficial ownership of any of the Subject Securities, except to the extent of any pecuniary interest therein.</footnote>
        <footnote id="F4">Mr. McGuire, a member of the board of directors of the Issuer of the Subject Securities, was elected to that board as a representative of the Reporting Persons. As a result, each of those persons are directors by deputization for purposes of Section 16 of the Securities Exchange Act of 1934.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>MARCATO CAPITAL MANAGEMENT LP, By: Marcato Holdings LLC, its General Partner, By: /s/ Richard McGuire III, Richard McGuire III, Managing Member</signatureName>
        <signatureDate>2018-02-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>MARCATO INTERNATIONAL MASTER FUND, LTD., By: /s/ Richard McGuire III, Richard McGuire III, Director</signatureName>
        <signatureDate>2018-02-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>MARCATO SPECIAL OPPORTUNITIES MASTER FUND LP, By: /s/ Richard McGuire III, Richard McGuire III, Director</signatureName>
        <signatureDate>2018-02-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Richard McGuire III, Richard McGuire III, Director</signatureName>
        <signatureDate>2018-02-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
