NMG 6-K

UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TORULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the monthof December 2025

Commission File Number: 001-40416

Nouveau MondeGraphite Inc.****(Translation of registrant’s name into English)

481 rue BrassardSaint-Michel-des-Saints, QuebecCanada J0K 3B0

(Address of principal executive office)

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

DOCUMENTS TO BE FILED AS PART OF THIS 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, there unto duly authorized.

Exhibit 99.1

DESIGNATED PRESS RELEASE For immediate release

NMGAnnounces Closing of US$20 Million Public Offering ofCommon Shares

MONTRÉAL,CANADA, December 19, 2025 – Nouveau Monde Graphite Inc. (“NMG“ or the “Company”) (NYSE: NMG, TSX: NOU) announces the closing of its previously announced public offering (the “Offering”) of 8,333,334 of its common shares (the “Common Shares”) at a price of US$2.40 per Common Share for aggregate gross proceeds of approximately US$20 million.

Maxim Group LLC acted as sole placement agent for the Offering (the “Placement Agent”).

The Company intends to use the net proceeds from the Offering for procurement of long-lead equipment, to initiate certain construction activities, and to cover detailed engineering and indirect costs for the Matawinie Mine project, to fund engineering activities to deliver an AACE class 3 estimate for the 13ktpy Bécancour Battery Material Plant project, and to fund general working capital and corporate expenditures.

In connection with the Offering, the Company has filed a final prospectus supplement (the “Prospectus Supplement”) to the Company’s existing base shelf prospectus dated December 5, 2025, filed in Canada (the “Base Shelf Prospectus”) and the Company's United States registration statement on Form F-10 (the “Registration Statement”) filed with the U.S. Securities and Exchange Commission (the “SEC”) under the United States Securities Act of 1933, as amended, pursuant to the Multi-Jurisdictional Disclosure System adopted by the United States and Canada. The Offering was made solely in the United States and permitted foreign jurisdictions, and no Common Shares have been offered or sold in Canada. The Prospectus Supplement filed in Canada (together with the related Base Shelf Prospectus) is available on SEDAR at www.sedarplus.ca. The Prospectus Supplement filed in the United States (together with the Registration Statement) is available on the SEC’s website at www.sec.gov. Copies of the Prospectus Supplement and accompanying Base Shelf Prospectus may be obtained by contacting Maxim Group LLC, at 300 Park Avenue, 16th Floor, New York, NY 10022, Attention: Syndicate Department, or by telephone at (212) 895-3745 or by email at [email protected].

This press release does not constitute an offer to sell or the solicitation of an offer to buy securities, nor will there be any sale of the securities in any province, state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such province, state or jurisdiction. The securities being offered and the contents of this press release have not been approved or disapproved by any regulatory authority, nor has any such authority passed upon the accuracy or adequacy of the Prospectus Supplement, the Base Shelf Prospectus or the Registration Statement.

About Nouveau Monde Graphite

NMG is an integrated company developing responsible mining and advanced processing operations to supply the global economy with carbon-neutral advanced graphite materials. The Company is developing in Québec, Canada, a fully integrated ore-to-processed-graphite value chain to serve tomorrow’s industries in energy, defense, technology, and manufacturing. With recognized ESG standards and structuring partnerships with major customers, NMG is set to become a strategic supplier of advanced materials to leading specialized manufacturers while promoting sustainability, innovation, and supply chain traceability. www.NMG.com

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Cautionary Note RegardingForward-Looking Information

This press release contains “forward-looking information” and “forward-looking statements” within the meaning of applicable securities legislation(collectively, “forward-looking statements”), including, but not limited to, statements relating to future events or futurefinancial or operating performance of the Company and reflect management’s expectations and assumptions regarding the Company’sgrowth, results, performance and business prospects and opportunities. Such forward-looking statements reflect management’s currentbeliefs and are based on information currently available to it. These forward-looking statements include, but are not limited to theintended use of proceeds from the Offering, the expected results of the initiatives described in this press release, and those statementswhich are discussed under the “About Nouveau Monde” paragraph and elsewhere in the press release which essentially describethe Company’s outlook and objectives.

Forward-looking statementsare based upon a number of estimates and assumptions that, while considered reasonable by the Company as of the time of such statements,are inherently subject to significant business, economic and competitive uncertainties that may cause the actual results, level of activity,performance, or achievement of the Company to be materially different from those expressed or implied by such forward-looking statements.

Many of these uncertaintiesand contingencies can directly or indirectly affect, and could cause, actual results to differ materially from those expressed or impliedin any forward-looking statements. There can be no assurance that forward-looking statements will prove to be accurate, as actual resultsand future events could differ materially from those anticipated in such statements. Forward-looking statements are provided for thepurpose of providing information about management’s expectations and plans relating to the future. The Company disclaims any intentionor obligation to update or revise any forward-looking statements or to explain any material difference between subsequent actual eventsand such forward-looking statements, except to the extent required by applicable law.

Neither the TSX nor NYSEaccepts responsibility for the adequacy or accuracy of this release.

Further information regarding the Companyis available in the SEDAR database (www.sedarplus.ca), and for United States readers on EDGAR (www.sec.gov), and on theCompany’s website at: www.NMG.com.