UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of February 2026

Commission File Number 001-40924

ALGOMA STEEL GROUP INC.

(Exact name of Registrant as specified in its charter)

N/A

(Translation of Registrant’s name into English)

105 West Street

Sault Ste. Marie, Ontario

P6A 7B4, Canada

(705) 945-2351

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F ☐   Form 40-F ☒

EXHIBIT INDEX

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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, thereunto duly authorized.

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Exhibit 99.1

MEDIA RELEASE

February 26, 2026

Algoma Steel Group Inc. to Announce 2025 Fourth Quarter and

Full Year Results March 11, 2026

SAULT STE. MARIE, Ontario, February 26, 2025 - Algoma Steel Group Inc. (NASDAQ: ASTL; TSX: ASTL) (“Algoma” or “the Company”), a leading Canadian producer of steel plate and hot rolled sheet products, announced today that the Company will release its 2025 fourth quarter and full year financial results after the market closes on Wednesday, March 11, 2026. A webcast and conference call will be held on Thursday, March 12, 2026 at 11:00 a.m. Eastern Time to review the Company’s results, discuss recent events, and conduct a question-and-answer session.

The live webcast and archived replay of the conference call can be accessed on the Investors section of the Company’s website at www.ir.algoma.com. For those unable to access the webcast, the conference call will be accessible domestically or internationally by dialing 877-425-9470 or 201-389-0878, respectively. Upon dialing in, please request to join the Algoma Steel Fourth Quarter 2025 Conference Call. To access the replay of the call, dial 844-512-2921 (domestic) or 412-317-6671 (international) with passcode 13758477.

About Algoma Steel

Based in Sault Ste. Marie, Ontario, Algoma is a leading Canadian producer of high-quality plate and sheet steel products, proudly supporting critical sectors including energy, defense, automotive, shipbuilding, and infrastructure. Guided by a purpose to build better lives and a greener future, Algoma is shaping the next generation of sustainable steelmaking in Canada.

With the transition to electric arc furnace (EAF) steelmaking and a modernized plate mill, Algoma is redefining how steel is made in Canada. Powered by Ontario’s clean electricity grid, this transformation represents one of the largest industrial decarbonization initiatives in North America and is expected to reduce carbon emissions by approximately 70% once fully transitioned. These advancements provide stability for continued investment in diversification projects aligned with Canada’s evolving needs.

This new chapter also introduces Volta^™, the brand for all steel produced through Algoma’s EAF technology. Volta delivers the same trusted performance customers rely on, with significantly lower emissions—produced safely, sustainably, and proudly in Canada.

Building on more than a century of steelmaking expertise, Algoma continues to invest in its people, processes, and technologies to strengthen domestic supply chains and deliver responsible, Canadian-made steel that helps build a better tomorrow.

Cautionary Statement Regarding Forward-Looking Statements

This news release contains “forward-looking information” under applicable Canadian securities legislation and “forward-looking statements” within the meaning of the U.S. Private Securities Litigation Reform Act of 1995 (collectively, “forward-looking statements”), including statements regarding the timing for the release of its financial results and the anticipated impact of Algoma’s EAF project on carbon emissions. These forward-looking statements generally are identified by the words “believe,” “project,” “expect,” “anticipate,” “estimate,” “intend,” “strategy,” “future,” “opportunity,” “plan,” “design,” “pipeline,” “may,” “should,” “will,” “would,” “will be,” “will continue,” “will likely result,” and similar expressions. Forward-looking statements are predictions, projections and other statements about future events that are based on current expectations and assumptions. Many factors could cause actual future events to differ materially from the forward-looking statements in this document. Readers should consider the risks and uncertainties set forth in the section entitled “Risk Factors” and “Cautionary Note Regarding Forward-Looking Information” in Algoma’s annual information form, filed by Algoma with the Ontario Securities Commission (the “OSC”) (available under the company’s SEDAR+ profile at www.sedarplus.ca) and with the SEC (available at www.sec.gov) as part of its annual report on Form 40-F, as well as in Algoma’s quarterly and current reports filed with the OSC and SEC. Forward-looking statements speak only as of the date they are made. Readers are cautioned not to put undue reliance on forward-looking statements, and Algoma assumes no obligation and does not intend to update or revise these forward-looking statements, whether as a result of new information, future events, or otherwise.

For more information, please contact:

Michael Moraca

Chief Financial Officer

Algoma Steel Group Inc.

Phone: 705.945.3300

E-mail: IR@algoma.com