UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15 (d) of

the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 25, 2013

McDermott International, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s Telephone Number, including Area Code: (281) 870-5000

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On March 25, 2013, McDermott International, Inc. (the “Borrower”) and certain of its wholly owned subsidiaries, as guarantors, entered into a second amendment and consent (“Amendment No. 2”) to the credit agreement dated May 3, 2010, among the Borrower, Crédit Agricole Corporate and Investment Bank, as administrative agent and collateral agent (in such capacity, the “Collateral Agent”), and certain lenders and letter of credit issuers party thereto (as amended August 19, 2011, the “Credit Agreement”).

Amendment No. 2 amended the Credit Agreement to, among other things: (1) release the Collateral Agent’s mortgage on the marine vessel McDermott Derrick Barge No. 30 (the “DB 30”); (2) permit the transfer of the DB 30 to a Malaysian joint venture in which the Borrower, indirectly through certain of its subsidiaries, has an interest (the “Malaysian JV”); (3) permit the Borrower to, directly or indirectly through subsidiaries, make a loan to the Malaysian JV without otherwise using the Credit Agreement’s investment baskets; and (4) permit the exchange of a portion of the equity issued by the Malaysian JV held through the Borrower’s subsidiaries for a portion of the equity issued by an unaffiliated Malaysian company that owns a fabrication yard.

In connection with entering into Amendment No. 2, the Borrower paid a consent fee to the lenders party thereto.

The foregoing summary is qualified in its entirety by reference to the complete text of Amendment No. 2, which is filed as Exhibit 4.1 to this report and is incorporated by reference herein.

The information provided under Item 1.01 above is incorporated by reference.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

March 28, 2013

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