Exhibit 5.1

January 31, 2023

5E Advanced Materials, Inc.

19500 State Highway 249, Suite 125

Houston, TX 77070

Re: Resale Registration Statement on Form S-1

Ladies and Gentlemen:

We have acted as special counsel to 5E Advanced Materials, Inc., a Delaware corporation (the “Company”), in connection with the Company’s registration statement on Form S-1 initially filed with the Securities and Exchange Commission (the “Commission”) on October 11, 2022 (the “Registration Statement”), under the Securities Act of 1933, as amended (the “Securities Act”). The Registration Statement relates to the registration by the Company of up to 4,581,534 shares (the “Conversion Shares”) of its Common Stock, par value $0.01 per share (the “Common Stock”), issuable upon conversion of the convertible notes described in the Registration Statement (the “Convertible Notes”) to be sold by the selling stockholders identified in the Registration Statement.

This opinion letter is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K promulgated under the Securities Act.

In rendering the opinion set forth below, we examined and relied upon such certificates, corporate records, agreements, instruments and other documents, and examined such matters of law, that we considered necessary or appropriate as a basis for the opinion, including the Certificate of Incorporation of the Company, filed as Exhibit 3.1 to the Registration Statement, and the Convertible Note Purchase Agreement, filed as Exhibit 10.14 to the Registration Statement. In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as copies and the authenticity of the originals of such latter documents. As to any facts material to the opinions expressed herein that we did not independently establish or verify, we have relied upon oral or written statements and representations of officers and other representatives of the Company and others.

Based upon the foregoing and subject to the assumptions, qualifications and limitations set forth herein, we are of the opinion that the Conversion Shares have been duly authorized and, when issued upon conversion of the Convertible Notes in accordance with the Convertible Note Purchase Agreement and the resolutions adopted by the Board of Directors of the Company, will be validly issued, fully paid and nonassessable.

January 31, 2023 Page 2

The opinions expressed herein are based upon and limited to the General Corporation Law of the State of Delaware, including the statutory provisions, the applicable provisions of the Delaware Constitution and reported judicial decisions interpreting the foregoing. We express no opinion herein as to any other laws, statutes, regulations or ordinances.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the reference to our firm under the caption “Legal Matters” in the prospectus included in the Registration Statement. In giving such consent, we do not thereby admit that we are experts within the meaning of the Securities Act or the rules and regulations of the Commission or that this consent is required by Section 7 of the Securities Act.

Very truly yours,

/s/ Winston & Strawn LLP

Winston & Strawn LLP