NexGen’s Final Batch of 2025 Assays Return Multiple High-Grade Intercepts

Confirming Both Expansion and Continuity of Primary High-Grade Subdomain and Confirmation of New High-Grade Subdomain at Depth

Highlights:

• RK-25-239 returns 13.0 m at 5.2% U₃O₈, including 0.5 m at 30.2% U₃O₈ confirming expansion of the growing high-grade subdomain 33 m up dip of RK-25-232 (15.0 m at 15.9% U₃O₈)

• RK-25-240 returns 10.0 m at 3.95% U₃O₈, including 0.5 m at 33.3% U₃O₈ in the down dip portion of the high-grade subdomain 266 m below RK-25-232

• Assays from RK-25-230 (7.5 m at 5.3% U₃O₈ including 0.5 m at 35.9% U₃O₈), RK-25-233 (6.0 m at 2.4% U₃O₈ including 0.5 m at 23.4% U₃O₈), RK-25-236 (5.5 m at 2.3% U₃O₈ including 0.5 m at 13.3% U₃O₈) confirm continuity of high-grade subdomain; 47 m, 151 m, and 40 m respectively from RK-25-232

• Confirmed the new high-grade subdomain, at 850 m below surface with RK-25-257 returning 4.5 m at 4.8% U₃O₈ including 0.5 m at 33.3% U₃O₈ located 67 m up dip of RK-24-202 (0.5 m at 6.9% U₃O₈). Confirms significant growth potential.

Vancouver, British Columbia–(Newsfile Corp. – May 7, 2026) – NexGen Energy Ltd. (TSX: NXE) (NYSE: NXE) (ASX: NXG) (“NexGen” or the “Company”) announces the final receipt of 2025 assay results that highlight the expansion and continuity of the high-grade subdomain at the Company’s 100% owned Patterson Corridor East (PCE) discovery located 3.5 km from the Arrow Deposit. The expansion of the high-grade subdomain is especially confirmed by RK-25-239 which returned 13.0 m at 5.2% U₃O₈, including 0.5 m at 30.2% U₃O₈, at 400 m below surface and RK-25-240 which returned 10.0 m at 3.95% U₃O₈, including 0.5 m at 33.3% U₃O₈, at 670 m below surface. Both of these holes share strong similarities with respect to their overall geological characteristics which span across 292 m of mineralized dip extent. (Figures 1-3, Table 1).

Results from RK-25-240 emphasize the potential extension of mineralization at depth where the system is open. Together with these results, the grades from RK-25-230 (Figure 4), RK-25-233, RK-25-236 have confirmed a strong core zone within the high-grade subdomain which remains open in most directions.

Within the overall mineralized footprint, a new secondary high-grade subdomain is now confirmed by RK-25-257 (Figures 1 and 5). This hole has several intercepts with the best being 4.5 m at 4.8% U₃O₈ including 0.5 m at 33.3% U₃O₈ located 67 m up dip of RK-24-202 (0.5 m at 6.9% U₃O₈). This new subdomain has high prospectivity for continued growth and is open in most directions.

Exploration drilling in 2026 has already driven further growth at PCE with the majority of the campaign (29,241.8 m of the planned 42,000 m) scheduled to recommence the week of May 25, 2026 (see news release April 22, 2026). All samples from 2026 drilling to date are submitted to the independent Saskatchewan Research Council Geoanalytical Laboratory (SRC), with results to follow.

Leigh Curyer, Founder & Chief Executive Officer, commented: “These assay results from 2025 drilling confirm high-grade mineralization and the expanding scale of PCE. The combination of high-grades, continuity, scale and geotechnical characteristics continue to highlight the similarities between PCE and the mighty Arrow Deposit. The opening up of a new high-grade subdomain emphasizes significant growth potential remains at PCE. With the structural supply deficit in the market widening, and the impacts of the industry wide underinvestment in the uranium supply chain for a generation, the urgency of finding and bringing online new, reliable uranium supply has never been greater. As the Rook I Project enters into major construction this summer, we continue to advance PCE to ensure that NexGen optimizes its unparalleled opportunity to become one of the world’s most important mining company in delivering energy fuel for the current and future generations.”

Figure 1: Interpreted PCE long section (as of April 22, 2026 release) with notable assays collected since discovery and new results outlined in red; view is a long section that looks perpendicular to the primary mineralized plane; total mineralized footprint in orange and the high-grade subdomains in red

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Figure 2: Core photo of assays from RK-25-239 with grades shown as % U₃O₈

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Figure 3: Core photo of assays from RK-25-240 with grades shown as % U₃O₈

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Figure 4: Core photo of assays from RK-25-230 with grades shown as % U₃O₈

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Figure 5: Core photo of assays from RK-25-257 highlighting the new subdomain with grades shown as % U₃O₈

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Table 1: Assays received since December 1, 2025 news release

• All depths and intervals are meters downhole, true thicknesses are yet to be determined.
• Unconformity of ‘N/A’ denotes a lack of visible contact between Athabasca sandstone and basement rock.
• Maximum internal dilution 2.0 m downhole.
• Minimum thickness of 0.5 m downhole.
• Cutoff grade 0.01% U₃O₈.
• All depths and intervals are metres downhole, true thicknesses are yet to be determined. Resource modelling in conjunction with an updated mineral resource estimate is required before true thicknesses can be determined.
• * Denotes results that correlate to high-grade levels of radioactivity (>10,000 cps)

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.

Natural gamma radiation in drill core reported in this news release was measured in counts per second (cps) using a Radiation Solutions Inc. RS-125 gamma spectrometer. The reader is cautioned that total count gamma readings may not be directly or uniformly related to uranium grades of the rock sample measured; they should be used only as a preliminary indication of the presence of radioactive minerals.

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 6, 2024 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.

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