Mr. Leigh Curyer reports

NEXGEN ANNOUNCES UPSIZED AUD $600 MILLION EQUITY OFFERING IN AUSTRALIA

NexGen Energy Ltd. has entered into an amended and restated underwriting agreement with Aitken Mount Capital Partners Pty. Ltd. to upsize its previously announced offering and pursuant to which the Australian underwriter has agreed to fully underwrite an offering of 45,801,527 common shares in the capital of the company, to be settled in the form of Australian CHESS depositary interests, at a price of $13.10 (Australian) per share, for gross proceeds of approximately $600-million (Australian). In accordance with a separate amended and restated appointment letter, Canaccord Genuity (Australia) Ltd. acted as joint lead manager (JLM) and bookrunner to the upsized Australian offering.

The company confirms that the book build for the upsized Australian offering has successfully closed.

As previously announced, concurrent with the Australian offering, the company also launched a bought deal equity offering with a syndicate of underwriters led by Merrill Lynch Canada Inc., under which the North American underwriters have agreed to buy on a bought deal basis 33,112,583 common shares in the capital of the company at a price of $12.08 (Canadian) per North American common share, the Canadian-dollar equivalent to the offering price (1), for gross proceeds of approximately $400-million (Canadian).

The company intends to use the net proceeds from the offering to advance engineering of the Rook I project, for Rook I preproduction capital costs and for general corporate purposes.

The North American common shares will be offered by way of a short form prospectus in all provinces and territories of Canada, other than Quebec, and will be offered in the United States pursuant to a prospectus filed as part of a registration statement under the Canada/U.S. multijurisdictional disclosure system. A registration statement on Form F-10, including the U.S. preliminary prospectus, registering the North American common shares under the U.S. Securities Act of 1933, as amended, has been filed with the United States Securities and Exchange Commission, but has not yet become effective. The preliminary prospectus and registration statement are subject to completion and amendment. Such documents contain important information about the North American offering.

The Australian common shares will be issued without disclosure under the Australian Corporations Act 2001 (Cth) to sophisticated investors and professional investors (within the meaning of subsections 708(8) and 708(11) of the Australian Corporations Act) and investors in other jurisdictions that may lawfully participate.

The offering is expected to close on or about Oct. 15, 2025 (EST), and is subject to the company receiving all necessary regulatory approvals, including conditional acceptance of the Toronto Stock Exchange and approval by the New York Stock Exchange. The preliminary prospectus is available on SEDAR+ . The registration statement is available on the SEC's website. The offered common shares to be sold in the offering described in this document may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. Before readers invest, they should read the prospectus in the registration statement and other documents the company has filed with Canadian regulatory authorities and the SEC for more complete information about the company and the offering. Potential investors may get any of these documents for free by visiting EDGAR on the SEC website or, when such documents become available, via SEDAR+, or the Australian Securities Exchange website. Copies of the prospectus relating to the North American offering may be obtained for free upon request in Canada by contacting Merrill Lynch Canada Inc., attention: Doug Butters, 181 Bay St., Suite 400, Toronto, Ont., M5J 2V8, by telephone at 416-369-3953, and in the United States by contacting BofA Securities, attention: prospectus department, 201 North Tryon St., Charlotte, N.C., 28255-0001, or by e-mail at dg.prospectus_requests@bofa.com.

The completion of the North American offering is not conditional upon the completion of the Australian offering and the completion of the Australian offering is not conditional upon the completion of the North American offering, and the North American underwriters have no obligations or liability with respect to the Australian offering and the Australian underwriter and the Australian JLM have no obligations or liability with respect to the North American offering.

About NexGen Energy Ltd.

NexGen Energy is a Canadian company focused on delivering clean energy fuel for the future. The company's flagship Rook I project is being optimally developed into the largest low-cost producing uranium mine globally, incorporating the most elite environmental and social governance standards. The Rook I project is supported by a National Instrument 43-101-compliant feasibility study, which outlines the elite environmental performance and industry-leading economics. NexGen is led by a team of experienced uranium and mining industry professionals with expertise across the entire mining life cycle, including exploration, financing, project engineering and construction, operations, and closure. NexGen is leveraging its proven experience to deliver a project that leads the entire mining industry socially, technically and environmentally. The project and prospective portfolio in northern Saskatchewan will provide generational, long-term economic, environmental and social benefits for Saskatchewan, Canada, and the world.

NexGen is listed on the Toronto Stock Exchange and the New York Stock Exchange under the ticker symbol NXE, and on the Australian Securities Exchange under the ticker symbol NXG, providing access to global investors to participate in NexGen's mission of solving three major global challenges in decarbonization, energy security and access to power. The company is headquartered in Vancouver, B.C., with its primary operations office in Saskatoon, Sask.

(1) Based on the Bloomberg exchange rate as quoted on Oct. 1, 2025 ($1 (Canadian) equal to $1.0850 (Australian))

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