Document

Exhibit 5.1



AMERICAS NEW YORK SAN FRANCISCO SÃO PAULO SILICON VALLEY WASHINGTON, D.C. ASIA HONG KONG SEOUL	One Liberty Plaza New York, NY 10006-1470 T: +1 212 225 2000 F: +1 212 225 3999 clearygottlieb.com D: +1 (212) 225-2130 ltsu@cgsh.com	EUROPE & MIDDLE EAST ABU DHABI BRUSSELS COLOGNE LONDON MILAN PARIS ROME

We have acted as special counsel to Somnigroup International, Inc., a Delaware corporation (the “Company”), in connection with the preparation and filing with the Securities and Exchange Commission (the “Commission”) of the Company’s registration statement on Form S-4 (including the documents incorporated by reference therein, the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”), relating to the shares of the Company’s common stock, par value $0.01 per share (the “Securities”), to be issued by the Company pursuant to the terms of the Agreement and Plan of Merger (the “Merger Agreement”), dated as of April 13, 2026, by and among the Company, Leggett & Platt, Incorporated, a Missouri corporation (“Leggett & Platt”) and Sparrow Unity Corporation, a Missouri corporation and a direct, wholly owned subsidiary of the Company (“Merger Sub”).

(e) certain resolutions of the board of directors of the Company relating to the approval of the Merger Agreement and the transactions contemplated thereby, including the issuance of the Securities, and certain related matters.

In addition, we have reviewed the originals or copies certified or otherwise identified to our satisfaction of all such corporate records of the Company and such other documents, and we

In rendering the opinion expressed below, we have assumed the authenticity of all documents submitted to us as originals and the conformity to the originals of all documents submitted to us as copies. In addition, we have assumed and have not verified the accuracy as to factual matters of each document we have reviewed.

Based on the foregoing, and subject to the further assumptions and qualifications set forth below, it is our opinion that, when the Registration Statement has become effective under the Securities Act, the Securities, when issued by the Company in accordance with the terms and conditions of the Merger Agreement, will be validly issued, fully paid and nonassessable.

In rendering the foregoing opinion, we have assumed that, prior to the issuance of Securities in connection with the consummation of the merger contemplated by the Merger Agreement: (i) the Registration Statement, as finally amended, will have become effective under the Securities Act; (ii) the merger will have been consummated in accordance with the terms of Merger Agreement; and (iii) the Securities will have been registered by the transfer agent and registrar for the shares of Company’s common stock, par value $0.01 per share.

We hereby consent to the use of our name in the prospectus constituting a part of the Registration Statement under the heading “Legal Matters,” as counsel for the Company that has passed on the validity of the Securities, and to the use of this opinion as a part (Exhibit 5.1) of the Registration Statement. In giving such consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder. The opinion expressed herein is rendered on and as of the date hereof, and we assume no obligation to advise you, or to make any investigations, as to any legal developments or factual matters arising subsequent to the date hereof that might affect the opinion expressed herein.


CLEARY GOTTLIEB STEEN & HAMILTON LLP

By:			/s/ Lillian Tsu
			Lillian Tsu, a Partner