Mr. David Cates reports

DENISON ANNOUNCES AWARD OF CONSTRUCTION MANAGEMENT CONTRACT TO WOOD CANADA FOR THE PHOENIX URANIUM MINE

Following a competitive tender process, Denison Mines Corp. has awarded Wood Canada Ltd., a global leader in consulting and engineering, with the construction management contract to oversee the building of the Phoenix in situ recovery (ISR) uranium mine. This is a key milestone for the project and represents another crucial step toward the commencement of construction.

David Cates, president and chief executive officer of Denison, commented: "In anticipation of receiving our federal permits to prepare the site and construct the Wheeler River project, we are pleased to announce the award of the construction management contract to our trusted partners at Wood. The selection of Wood for construction management allows us to leverage our long-standing relationship with Wood's Canadian team, which began with co-authoring the 2023 feasibility study for Phoenix and continued with the detailed design engineering for the project over the last two years.

"We are actively organizing our teams, including the onboarding of key construction personnel, to ensure we are ready to proceed with site preparation as soon as possible upon receipt of all required permits. Given Denison's strong balance sheet and advanced state of project engineering, construction planning and procurement, we stand ready to make a final investment decision and commence construction shortly after securing federal approval of the environmental assessment and licence to prepare the site for and construct a mine and mill."

John Day, president of projects, western hemisphere, at Wood, commented: "We value Denison's continued trust in our team and look forward to working together to lead the Wheeler River project through the construction phase. Having supported Phoenix from the feasibility stage through detailed design, we understand the technical and execution requirements of this project.

"Our priority is to enable a safe and seamless transition into execution -- maintaining continuity of personnel, applying disciplined project management and ensuring a predictable path to first production for this landmark project in the Canadian uranium industry. We look forward to continuing to work as an integrated team with Denison, combining our complementary project, construction and uranium expertise to deliver Phoenix safely and successfully."

The construction management contract currently contemplates procurement and construction management scopes, whereby Wood will be responsible for: (i) construction management of the full processing plant scope; (ii) installation of certain site infrastructure; and (iii) integrated project controls, continuing procurement support, on-site safety oversight, as well as maintaining reporting and performance management standards. The services will be provided by Wood in close consultation with Denison, with members of Wood's team and Denison's team holding complementary roles in an integrated project management team.

The selection of Wood for the construction management contract provides important continuity between the engineering and execution phases of the project and aims to enable the efficient and reliable delivery of the project during an estimated 24-month construction period. Denison has entered into the construction management contract as the operator of the project on behalf of the Wheeler River joint venture.

About Wheeler River

Wheeler River is the largest undeveloped uranium project in the infrastructure-rich eastern portion of the Athabasca basin region in Northern Saskatchewan. The project is host to the high-grade Phoenix and Gryphon uranium deposits, discovered by Denison in 2008 and 2014, respectively, and is a joint venture between Denison (90 per cent and operator) and JCU (Canada) Exploration Company Ltd. (10 per cent). In August, 2023, Denison filed a technical report summarizing the results of: (i) a Phoenix feasibility study; and (ii) a cost update to the 2018 prefeasibility study for conventional underground mining of the basement-hosted Gryphon uranium deposit. Based on the respective studies, both deposits have the potential to be competitive with the lowest-cost uranium mining operations in the world. Permitting efforts for the planned Phoenix ISR operation commenced in 2019 and are nearing completion with approval in July, 2025, of the project's enviromental assessment by the Province of Saskatchewan and conclusion in December, 2025, of the Canadian Nuclear Safety Commission Public Hearing for federal approval of the enviromental assessment and project construction licence. More information is available in the technical report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada," dated Aug. 8, 2023, with an effective date of June 23, 2023, and an update to estimated Phoenix initial capital costs disclosed by press release dated Jan. 2, 2026, copies of which are available on Denison's website and under its profile on SEDAR+ and on EDGAR.

About Denison Mines Corp.

Denison is a leading uranium mining, development and exploration company with interests focused in the Athabasca basin region of Northern Saskatchewan, Canada. In addition to Denison's effective 95-per-cent interest in its flagship Wheeler River project, Denison's interests in Saskatchewan include a 22.5-per-cent ownership interest in the McClean Lake joint venture (MLJV), which includes unmined uranium deposits (with mining at McClean North deposit through the MLJV's Sabre mining method, having commenced in 2025 using the MLJV's Sabre mining method) and the McClean Lake uranium mill (currently utilizing a portion of its licensed capacity to process the ore from the Cigar Lake mine under a toll milling agreement), plus a 25.17-per-cent interest in the Midwest joint venture Midwest Main and Midwest A deposits and a 70.55-per-cent interest in the Tthe Heldeth Tue (THT) and Huskie deposits on the Waterbury Lake property. The Midwest Main, Midwest A, THT and Huskie deposits are located within 20 kilometres of the McClean Lake mill. Taken together, Denison has direct ownership interests in properties covering approximately 457,000 hectares in the Athabasca basin region.

Additionally, through its 50-per-cent ownership of JCU, Denison holds interests in various uranium project joint ventures in Canada, including the Millennium project (JCU: 30.099 per cent), the Kiggavik project (JCU: 33.8118 per cent) and Christie Lake (JCU: 34.4508 per cent).

In 2024, Denison celebrated its 70th year in uranium mining, exploration and development, which began in 1954 with Denison's first acquisition of mining claims in the Elliot Lake region of Northern Ontario.

Technical disclosure and qualified person

The technical information contained in this press release has been reviewed and approved by Chad Sorba, PGeo, Denison's vice-president, technical services and project evaluation, who is a qualified person in accordance with the requirements of National Instrument 43-101.

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