6-K

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

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of March2026

Commission File Number: 001-39240

GFL Environmental Inc.

(Translation of registrant’s name intoEnglish)

1759 Purdy Avenue, Suite 300

Miami Beach, Florida33139

(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 x

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ¨

EXHIBIT INDEX

The following Exhibit 99.1 is furnished as part of this Current Report on Form 6-K.

SIGNATURE

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.

Exhibit99.1

GFLEnvironmental Inc. Sets Date for Q1 2026 Earnings Release

MIAMI BEACH, FL, March 27, 2026 – GFL Environmental Inc. (NYSE: GFL) (TSX: GFL) (“GFL” or the “Company”) today announced that it will release its 2026 first quarter financial results after the market closes on Wednesday April 29, 2026 and will host an investor conference call related to this release on Thursday April 30, 2026 at 8:30 am Eastern Time.

A live audio webcast of the conference call can be accessed by logging onto the Company's Investors page at investors.gflenv.com or by clicking here or listeners may access the call toll-free by dialing 1-833-950-0062 in Canada or 1-833-470-1428 in the United States (access code: 627968) approximately 15 minutes prior to the scheduled start time.

The Company encourages participants who will be dialing in to pre-register for the conference call using the following link: https://www.netroadshow.com/events/login/LE9zwo3jkZr3ni9X4o4KwiGrPb70n6aKQZm. Callers who pre-register will be given a conference access code and PIN to gain immediate access to the call and bypass the live operator on the day of the call.

AboutGFL

GFL is the fourth largest diversified environmental services company in North America, providing comprehensive solid waste management services from its platform of facilities throughout Canada and 18 U.S. states. GFL has a workforce of more than 15,000 employees across its organization.

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