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): November 27, 2015

Mallinckrodt public limited company

(Exact name of registrant as specified in its charter)

Perth House, Millennium Way

Chesterfield, Derbyshire, United Kingdom S41 8ND

(Address of principal executive offices)

+44 124 626 3051

(Registrant’s telephone number, including area code)

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 November 27, 2015, Mallinckrodt Group S.à r.l., Mallinckrodt U.S. Holdings Inc., Mallinckrodt Netherlands Holdings B.V., Mallinckrodt Finance GmbH, Ludlow Corporation, Mallinckrodt Holdings GmbH, and Mallinckrodt International Finance S.A., (collectively, the “Sellers”), each a subsidiary of Mallinckrodt plc (the “Company”), completed the previously disclosed sale of (i) the Company’s contrast media and delivery systems business, which primarily consists of the selling, marketing, distributing, manufacturing and servicing of diagnostic contrast media products and delivery devices (the “CMDS Business”) and (ii) the Company’s Urology business, which primarily consists of selling, marketing, distributing, servicing and assembling urology imaging systems (the “Urology Business” and, collectively, the “Business”), to Guerbet S.A. (the “Buyer”) in exchange for $270 million in cash pursuant to that certain Stock Purchase Agreement, dated as of July 27, 2015, by and among the Sellers and Buyer, as amended by that First Amendment to Stock Purchase Agreement, dated as of November 27, 2015, by and among the Sellers and Buyer (as amended, the “Purchase Agreement”). The purchase price is subject to customary post-closing adjustments for levels of cash, indebtedness and net working capital at closing.

The foregoing summary of the transactions contemplated thereby does not purport to be complete and is subject to, and qualified in its entirety by, the full text of the Purchase Agreement filed herewith as Exhibit 2.1 and Exhibit 2.2, which are incorporated herein by reference.

The Purchase Agreement has been included to provide investors with information regarding its terms. It is not intended to provide any other factual information about the Company, Sellers or Buyer or any of their affiliates, their respective businesses, or the actual conduct of their respective businesses during the period prior to the closing of the transactions contemplated by the Purchase Agreement. The Purchase Agreement contains representations and warranties that are the product of negotiations among the parties thereto and that the parties made to, and solely for the benefit of, each other as of specified dates. The assertions embodied in those representations and warranties are subject to qualifications and limitations agreed to by the respective parties and are also qualified in important part by a confidential disclosure schedule delivered by Sellers in connection with the Purchase Agreement. The representations and warranties may have been made for the purpose of allocating contractual risk between the parties to the Purchase Agreement instead of establishing these matters as facts, and may be subject to standards of materiality applicable to the contracting parties that differ from those applicable to investors.

On November 27, 2015, the Company issued a press release announcing, among other things, the completion of the sale of the Business. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated in this Item 7.01 by reference

(d) Exhibits.

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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 hereunto duly authorized.

Dated: November 27, 2015

Exhibit Index