• RK-25-232 intersects broad zone of intense mineralization including 3.9 m of >61,000 cps
• High-grade subdomain doubles in size to 210 m strike and 335 m vertical extent
• Represents best hole drilled at any NexGen property, including Arrow, during the discovery-phase of exploration

NexGen Energy Ltd. (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.

Drillhole RK-25-232 intersected 3.9 meters 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.

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

Table 1: 2025 Spectrometer results as of March 13

• All depths and intervals are meters downhole, true thicknesses are yet to be determined.
• “Off-scale” refers to >61,000 cps total readings by gamma spectrometer type RS-125.
• “Anomalous” means >500 cps (counts per second) total count gamma readings by gamma scintillometer type RS-120.
• Where “CPS Range” is <500 cps, this refers to local low radiometric zones within the overall radioactive interval.
• Unconformity of ‘N/A’ denotes a lack of visible contact between Athabasca sandstone and basement rock.
• Maximum internal dilution 2.0 m downhole.
• 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.

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.

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 (CNW Group/NexGen Energy Ltd.)

Figure 2: Zoomed view of RK-25-232 and surrounding pierce points on the long section, significant space to be tested in all directions (CNW Group/NexGen Energy Ltd.)

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 (CNW Group/NexGen Energy Ltd.)

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 (CNW Group/NexGen Energy Ltd.)