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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-11-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000100493</issuerCik>
        <issuerName>TYSON FOODS INC</issuerName>
        <issuerTradingSymbol>TSN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001592292</rptOwnerCik>
            <rptOwnerName>Carper Howell P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2200 DON TYSON PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPRINGDALE</rptOwnerCity>
            <rptOwnerState>AR</rptOwnerState>
            <rptOwnerZipCode>72762</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP Strategy and New Ventures</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>22226.447</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>163081.3915</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10859</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>152222.3915</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8432.475</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>160654.8665</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5986.5086</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Employee Stock Purchase Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23347</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23347.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F5"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>33729.90</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>33729.9</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33729.90</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Qualified Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>50.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F6"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>36759</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2016-11-30</value>
            </exerciseDate>
            <expirationDate>
                <value>2025-11-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>36759.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>36759</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On November 26, 2012 the Reporting Person received a grant of performance shares which vested or expired on November 30, 2015 subject to the achievement of performance criteria in the applicable Stock Incentive Agreement.  The performance criteria were (a) a cumulative adjusted earnings before interest and taxes (EBIT) target of $3,844 million for the 2013-2015 fiscal years and (b) a favorable comparison of the Issuer's Class A common stock price relative to the stock prices of a predetermined peer group of publicly traded companies over the 2013-2015 fiscal years. The performance shares could vest at a level of 50%-200% and were previously reported as derivative securities at the 200% level. On November 30, 2015, 22,226.447 shares vested and are reported herein as acquired non-derivatives securities.</footnote>
        <footnote id="F2">Includes 9,278.9249 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2016 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved; and 7,766.0196 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved.</footnote>
        <footnote id="F3">Pursuant to an election made by the Reporting Person, these shares were sold by the Reporting Person to the Issuer on November 30, 2015, to satisfy tax withholding obligations related to the vesting described in footnote 2.</footnote>
        <footnote id="F4">Award of Class A Common Stock which vests on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2018 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved. The performance criterion is achievement of a three year (fiscal 2016-2018) cumulative EBIT target as set forth in the Stock Incentive Agreement. If the performance criterion is not achieved, the award expires.</footnote>
        <footnote id="F5">Award of performance Class A Common Stock which vests on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2018 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved. The performance criteria set forth in the Stock Incentive Agreement are (1) achievement of a three year (fiscal 2016-2018) cumulative EBIT target and (2) a favorable comparison of the market price of the Issuer's Class A Common Stock to a predetermined peer group of publicly traded companies over a three year (fiscal 2016-2018) period. Subject to the achievement of the performance criteria, the performance shares could vest at a level of 50%-200% and are reported as derivative securities at the 200% level. If neither of the performance criteria is achieved, the award expires.</footnote>
        <footnote id="F6">The stock options vest at 33 1/3% on each of the first, second, and third anniversary dates of the grant.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Howell P. Carper</signatureName>
        <signatureDate>2015-12-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "wf-form4_144908370524939.xml", "description": "FORM 4", "secsgml_size_bytes": 16121}]
X0306
4
2015-11-30
0
0000100493
TYSON FOODS INC
TSN
0001592292
Carper Howell P
2200 DON TYSON PARKWAY
SPRINGDALE
AR
72762
0
1
0
0
EVP Strategy and New Ventures
Class A Common Stock
2015-11-30
4
M
0
22226.447
0
A
163081.3915
D
Class A Common Stock
2015-11-30
4
S
0
10859
50
D
152222.3915
D
Class A Common Stock
2015-11-30
4
A
0
8432.475
0
A
160654.8665
D
Class A Common Stock
5986.5086
I
Employee Stock Purchase Plan
Performance Shares
2015-11-30
4
M
0
23347
0
D
Class A Common Stock
23347.0
0
D
Performance Shares
2015-11-30
4
A
0
33729.90
A
Class A Common Stock
33729.9
33729.90
D
Non-Qualified Stock Options (Right to Buy)
50.0
2015-11-30
4
A
0
36759
50
A
2016-11-30
2025-11-30
Class A Common Stock
36759.0
36759
D
On November 26, 2012 the Reporting Person received a grant of performance shares which vested or expired on November 30, 2015 subject to the achievement of performance criteria in the applicable Stock Incentive Agreement.  The performance criteria were (a) a cumulative adjusted earnings before interest and taxes (EBIT) target of $3,844 million for the 2013-2015 fiscal years and (b) a favorable comparison of the Issuer's Class A common stock price relative to the stock prices of a predetermined peer group of publicly traded companies over the 2013-2015 fiscal years. The performance shares could vest at a level of 50%-200% and were previously reported as derivative securities at the 200% level. On November 30, 2015, 22,226.447 shares vested and are reported herein as acquired non-derivatives securities.
Includes 9,278.9249 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2016 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved; and 7,766.0196 shares of Class A Common Stock which vest on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2017 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved.
Pursuant to an election made by the Reporting Person, these shares were sold by the Reporting Person to the Issuer on November 30, 2015, to satisfy tax withholding obligations related to the vesting described in footnote 2.
Award of Class A Common Stock which vests on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2018 fiscal year if the performance criterion described in the applicable Stock Incentive Agreement is achieved. The performance criterion is achievement of a three year (fiscal 2016-2018) cumulative EBIT target as set forth in the Stock Incentive Agreement. If the performance criterion is not achieved, the award expires.
Award of performance Class A Common Stock which vests on the fourth business day following the filing of the Issuer's Annual Report on Form 10-K for its 2018 fiscal year if the performance metrics described in the applicable Stock Incentive Agreement are achieved. The performance criteria set forth in the Stock Incentive Agreement are (1) achievement of a three year (fiscal 2016-2018) cumulative EBIT target and (2) a favorable comparison of the market price of the Issuer's Class A Common Stock to a predetermined peer group of publicly traded companies over a three year (fiscal 2016-2018) period. Subject to the achievement of the performance criteria, the performance shares could vest at a level of 50%-200% and are reported as derivative securities at the 200% level. If neither of the performance criteria is achieved, the award expires.
The stock options vest at 33 1/3% on each of the first, second, and third anniversary dates of the grant.
/s/ Howell P. Carper
2015-12-02