Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement Nos. 333-189711, 333-189712, 333-189716, 333-196054, 333-203912, 333-211117 and 333-230234 on Form S-8 of our reports relating to the consolidated financial statements and financial statement schedule of Mallinckrodt plc, and the effectiveness of Mallinckrodt plc’s internal control over financial reporting dated February 25, 2020, appearing in the Annual Report on Form 10-K of Mallinckrodt plc for the fiscal year ended December 27, 2019.

/s/ DELOITTE & TOUCHE LLP

St. Louis, Missouri

February 25, 2020