NexGen Energy Solidifies 100% Ownership of Its Entire Land Package

• NexGen acquires Rio Tinto's 10% production carried interest over 39 NexGen-owned mineral claims in the Southwest Athabasca Basin, including those hosting the Patterson Corridor East (PCE) discovery.

• NexGen now owns exclusively 100% of its entire portfolio of Projects and Properties which include Rook I (location of Arrow and PCE deposits), SW1 and SW3.

Vancouver, British Columbia--(Newsfile Corp. - July 24, 2025) - NexGen Energy Ltd. (TSX: NXE) (NYSE: NXE) (ASX: NXG) ("NexGen" or the "Company") is pleased to announce it has exercised its Right of First Refusal to acquire the 10% production carried interest (PCI) held by Rio Tinto Exploration Canada Inc. (Rio Tinto) over 39 of NexGen's mineral claims in the Southwest Athabasca Basin, including those hosting the PCE discovery (Figure 1). NexGen's entire portfolio including the Arrow deposit is now 100% owned (Figure 2). Concurrent with its exercise, NexGen has agreed to match a cash payment offered to Rio Tinto for the interest, the terms of which are contractually confidential.

Leigh Curyer, Chief Executive Officer, commented: "Given the world class extent, high grade and superior technical setting of mineralization discovered to date at our two projects, consolidating our portfolio at PCE and surrounding area to match our 100% ownership in our world-class Arrow deposit, is entirely in line with our strategic objective of becoming the future leader in uranium production worldwide.

Today, the uranium market is already in a structural deficit. With the world's leading tech companies recently committing to the construction of over US$100BN in AI data centres in the US alone - to be predominantly powered by nuclear energy - the ever-growing need for a safe, secure supply of uranium from sound jurisdictions is upon us. NexGen's unmatched uranium endowment, including our flagship Arrow and developing PCE deposit, together with our large surrounding land package meets that criteria. Today's transaction further elevates the realisation of our long-standing strategic objective of becoming the largest supplier of uranium worldwide."

History

The PCI entitled Rio Tinto to a 10% undivided interest in future production from the subject claims, carried through to the commencement of commercial production, and was put in place before NexGen acquired the land package in 2012. Upon commencement of production, NexGen was entitled to recover 10% of all prior costs incurred from the effective date of the original agreement, from 75% of Rio Tinto's 10% share of production. Following full recovery of those costs, Rio Tinto would have received its full 10% share of production. A joint venture would have been formed at that time to govern ongoing operations.

Figure 1: Previous Rio Tinto PCI over 39 total claims held by NexGen

Figure 2: Previous PCI claims over Rook I Project which covered PCE

About NexGen

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 an N.I. 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, 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, British Columbia, with its primary operations office in Saskatoon, Saskatchewan.

Technical Disclosure*

All technical information in this news release has been reviewed and approved by Jason Craven, NexGen's Vice President, Exploration, a qualified person under National Instrument 43-101. A technical report in respect of the FS is filed on SEDAR+ (www.sedarplus.ca) and EDGAR (www.sec.gov/edgar.shtml) and is available for review on NexGen Energy's website (www.nexgenenergy.ca).

Cautionary Note to U.S. Investors

This news release includes Mineral Reserves and Mineral Resources classification terms that comply with reporting standards in Canada and the Mineral Reserves and the Mineral Resources estimates are made in accordance with NI 43-101. NI 43-101 is a rule developed by the Canadian Securities Administrators that establishes standards for all public disclosure an issuer makes of scientific and technical information concerning mineral projects. These standards differ from the requirements of the Securities and Exchange Commission ("SEC") set by the SEC's rules that are applicable to domestic United States reporting companies. Consequently, Mineral Reserves and Mineral Resources information included in this news release is not comparable to similar information that would generally be disclosed by domestic U.S. reporting companies subject to the reporting and disclosure requirements of the SEC Accordingly, information concerning mineral deposits set forth herein may not be comparable with information made public by companies that report in accordance with U.S. standards.

Forward-Looking Information

The information contained herein contains "forward-looking statements" within the meaning of applicable United States securities laws and regulations and "forward-looking information" within the meaning of applicable Canadian securities legislation. "Forward-looking information" includes, but is not limited to, statements with respect to mineral reserve and mineral resource estimates, the 2021 Arrow Deposit, Rook I Project and estimates of uranium production, grade and long-term average uranium prices, anticipated effects of completed drill results on the Rook I Project, planned work programs, completion of further site investigations and engineering work to support basic engineering of the project and expected outcomes. Generally, but not always, forward-looking information and statements can be identified by the use of words such as "plans", "expects", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or "believes" or the negative connotation thereof or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur" or "be achieved" or the negative connotation thereof. Statements relating to "mineral resources" are deemed to be forward-looking information, as they involve the implied assessment that, based on certain estimates and assumptions, the mineral resources described can be profitably produced in the future.

Forward-looking information and statements are based on the then current expectations, beliefs, assumptions, estimates and forecasts about NexGen's business and the industry and markets in which it operates. Forward-looking information and statements are made based upon numerous assumptions, including among others, that the mineral reserve and resources estimates and the key assumptions and parameters on which such estimates are based are as set out in this news release and the technical report for the property , the results of planned exploration activities are as anticipated, the price and market supply of uranium, the cost of planned exploration activities, that financing will be available if and when needed and on reasonable terms, that third party contractors, equipment, supplies and governmental and other approvals required to conduct NexGen's planned exploration activities will be available on reasonable terms and in a timely manner and that general business and economic conditions will not change in a material adverse manner. Although the assumptions made by the Company in providing forward-looking information or making forward-looking statements are considered reasonable by management at the time, there can be no assurance that such assumptions will prove to be accurate in the future.

Forward-looking information and statements also involve known and unknown risks and uncertainties and other factors, which may cause actual results, performances and achievements of NexGen to differ materially from any projections of results, performances and achievements of NexGen expressed or implied by such forward-looking information or statements, including, among others, the existence of negative operating cash flow and dependence on third party financing, uncertainty of the availability of additional financing, the risk that pending assay results will not confirm previously announced preliminary results, conclusions of economic valuations, the risk that actual results of exploration activities will be different than anticipated, the cost of labour, equipment or materials will increase more than expected, that the future price of uranium will decline or otherwise not rise to an economic level, the appeal of alternate sources of energy to uranium-produced energy, that the Canadian dollar will strengthen against the U.S. dollar, that mineral resources and reserves are not as estimated, that actual costs or actual results of reclamation activities are greater than expected, that changes in project parameters and plans continue to be refined and may result in increased costs, of unexpected variations in mineral resources and reserves, grade or recovery rates or other risks generally associated with mining, unanticipated delays in obtaining governmental, regulatory or First Nations approvals, risks related to First Nations title and consultation, reliance upon key management and other personnel, deficiencies in the Company's title to its properties, uninsurable risks, failure to manage conflicts of interest, failure to obtain or maintain required permits and licences, risks related to changes in laws, regulations, policy and public perception, as well as those factors or other risks as more fully described in NexGen's Annual Information Form dated March 3, 2025 filed with the securities commissions of all of the provinces of Canada except Quebec and in NexGen's 40-F filed with the United States Securities and Exchange Commission, which are available on SEDAR+ at www.sedarplus.ca and Edgar at www.sec.gov.

Although the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in the forward-looking information or statements or implied by forward-looking information or statements, there may be other factors that cause results not to be as anticipated, estimated or intended. Readers are cautioned not to place undue reliance on forward-looking information or statements due to the inherent uncertainty thereof.

There can be no assurance that forward-looking information and statements will prove to be accurate, as actual results and future events could differ materially from those anticipated, estimated or intended. Accordingly, readers should not place undue reliance on forward-looking statements or information. The Company undertakes no obligation to update or reissue forward-looking information as a result of new information or events except as required by applicable securities laws.