Exhibit 99.1

NexGen Announces Best Ever Discovery-Phase Intercept At Rook I Property

Vancouver, BC, March 24, 2025 - NexGen Energy Ltd. ("NexGen" or the "Company") (TSX: NXE) (NYSE: NXE) (ASX: NXG) is excited to announce the best hole drilled to date, RK-25-232 (Figures 1 and 2). This hole has materially expanded the shallow inner high-grade subdomain at Patterson Corridor East (PCE).

Drillhole RK-25-232 intersected 3.9 meters (“m”) of >61,000 cps, indicating rich uranium concentration within a larger 13.8 m mineralized interval that starts at 452.2 m (Figures 3 and 4, Table 1). It is one of the shallowest high-grade intersections at PCE and open in all directions (including 300 m up dip) within the competent basement rock. Four additional winter drillholes all located a minimum 50 m from RK-25-232 have all encountered high-grade intercepts containing >61,000 cps (RK-25-227, -230, -233, -236) expanding the high-grade subdomain to 210 m along strike and 335 m of vertical extent, doubling in size since last reported in November 2024 (previously 100 m strike and 170 m vertical extent). Ongoing exploration will focus on growing and defining this high-grade zone from hole RK-25-232.

Leigh Curyer, Chief Executive Officer, commented: “This intercept from RK-25-232 is geologically exceptional and represents a transformational moment taking PCE into a category to rival Arrow at the same stage of drilling. Discovering mineralization of this intensity so early in our 2025 program outpaces the success pattern experienced at the Arrow Deposit. Incredible, considering Arrow’s status on the world stage. To put this into context, the width of high-grade intense mineralization in RK-25-232 at PCE was first encountered at Arrow well into the delineation phase of resource definition. Together with Arrow, it’s validation a very significant regional mineralizing event has occurred at Rook I that we are only just beginning to assess the magnitude.

Today’s result comes at a time the need for Canada to optimize the development of its energy fuel resources has never been more important. NexGen, Saskatchewan and our community partners are ready to immediately commence construction of the Rook I Project subject to the completion of the CNSC approval process.”

Jason Craven, Vice President, Exploration, commented: “Another exciting evaluation milestone has been achieved by intersecting the surge of mineralization intensity in RK-25-232. Vein-type uranium is known to have high-grade zones within broad, structurally controlled footprints. Our focus is to expand the high-grade subdomain while also investigating for natural repetition within the evolving mineralized footprint, all of which is very similar to the approach to Arrow’s resource development.”

The development of PCE has advanced quickly over the past year; from an initial discovery of new vein-type basement-hosted uranium in February 2024, to a rapidly growing mineralized footprint and expanding high-grade, and now to a best-ever high-grade intersection in RK-25-232. An interpreted 3D model (Figures 1 and 2) provides a new visual representation of the scale and setting of the mineralization.

This is a Designated News Release

Reporting of assays from 2024 is expected in April once all results have been received and verified.

Figure 1: Interpreted model of mineralization at PCE (as of this release) and same exploration stage of the A2 shear mineralization from Arrow (as of Spring 2015); both are shown on long sections that look perpendicular to their primary mineralized planes; total mineralized footprint in orange and the high-grade subdomains in red; 2019 Feasibility Study notes 174.2 Mlbs U3O8 measured and indicated hosted by final A2

Figure 2: Zoomed view of RK-25-232 and surrounding pierce points on the long section, significant space to be tested in all directions Figure 3: Core photo of mineralization from RK-25-232; off-scale high-grade mineralization is near continuous within an overall vein width of 13.8 m from 452.2 to 466.0 m; yellow outlines >1,000 cps, red outlines >10,000 cps, purple outlines >61,000 cps

Figure 4: Massive replacement by uranium mineralization at 460.6 m in RK-25-232; examples of this intense mineralization style are spread throughout the high-grade subdomain

Table 1: 2025 Spectrometer results as of March 13

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.

Contact Information

Leigh Curyer

Chief Executive Officer
NexGen Energy Ltd.

+1 604 428 4112
lcuryer@nxe-energy.ca

www.nexgenenergy.ca

Travis McPherson

Chief Commercial Officer

NexGen Energy Ltd.

+1 604 428 4112

tmcpherson@nxe-energy.ca

www.nexgenenergy.ca

Monica Kras

Vice President, Corporate Development

NexGen Energy Ltd.

+44 7307 191933

mkras@nxe-energy.ca
www.nexgenenergy.ca

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.sedar.com ) 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.sedar.com 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.