Phoenix Feasibility Study 2023

Cautionary Statements & References Denison This presentation and the information contained herein is designed to help you understand management's current views, and may not be appropriate for other purposes. This presentation contains third-party information, such as the uranium market, other issuers, provincial and federal infrastructure and regulations, etc., derived from third-party publications and reports which Denison believes are reliable but have not been independently verified by the Company. Certain information contained in this presentation constitutes "forward-looking information", within the meaning of the United States Private Securities Litigation Reform Act of 1995 and similar Canadian legislation concerning the business, operations and financial performance and condition of Denison. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as "plans", "expects", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or "believes", or the negatives and / or variations of such words and phrases, or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur", "be achieved" or "has the potential to". In particular, this presentation contains forward-looking information pertaining to the results of, and estimates, assumptions and projections provided in, the 2023 Phoenix feasibility study ("Phoenix FS"), the 2023 Gryphon PFS Update ("Gryphon PFS Update") and the Waterbury PEA, including future development methods and plans, market prices, costs and capital expenditures; de-risking and project assessment activities, plans and objectives; assumptions regarding Denison's ability to obtain all necessary regulatory approvals to commence development at Wheeler; Denison's percentage interest in its projects and assumed continuity of its agreements with its joint venture partners and other third parties; production and SABRE development outlook for McClean Lake; and estimates of uranium industry factors, including physical uranium supply and demand. Statements relating to "mineral resources" are deemed to be forward-looking information, as they involve the implied assessment, based on certain estimates and assumptions that the mineral resources described can be profitably produced in the future. Forward looking statements are based on the opinions and estimates of management as of the date such statements are made, and they are subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of Denison to be materially different from those expressed or implied by such forward-looking statements. Denison faces certain risks, including the proposed use of mining methods which are novel and untested in the Athabasca basin, the inability to permit or develop its projects as currently planned, the inability to secure sufficient financing to pursue its business objectives, the unpredictability of market prices, events that could materially increase costs, changes in the regulatory environment governing the project lands, and unanticipated claims against title and rights to the project. Denison believes that the expectations reflected in this forward-looking information are reasonable but there can be no assurance that such statements will prove to be accurate and may differ materially from those anticipated in this forward looking information. For a discussion in respect of risks and other factors that could influence forward-looking events, please refer to the "Risk Factors" in the Annual Information Form dated March 27, 2023 available under its profile on SEDAR+ at www.sedarplus.ca and Annual Report on Form 40-F available on EDGAR at www.sec.gov/edgar.shtml. These factors are not, and should not be construed as being, exhaustive. Readers should not place undue reliance on forward-looking statements. The forward-looking information contained in this presentation is expressly qualified by this cautionary statement. Any forward-looking information and the assumptions made with respect thereto speaks only to the effective date of this presentation. Denison does not undertake any obligation to publicly update or revise any forward-looking information after such date to conform such information to actual results or to changes in its expectations except as otherwise required by applicable legislation. Cautionary Note to United States Investors Concerning Estimates of Mineral Resources and Mineral Reserves: This presentation may use terms such as "measured", "indicated" and/or "inferred" mineral resources and "proven" or "probable" mineral reserves, which are terms defined with reference to the guidelines set out in the Canadian Institute of Mining, Metallurgy and Petroleum ("CIM") CIM Definition Standards on Mineral Resources and Mineral Reserves ("CIM Standards"). The Company's descriptions of its projects may not be comparable to similar information made public by U.S. companies subject to the reporting and disclosure requirements under the United States federal securities laws and the rules and regulations thereunder. Qualified Persons The disclosure of a scientific or technical nature within this presentation, including the disclosure of mineral resources, mineral reserves, and the results of the Phoenix FS, Gryphon PFS Update and Waterbury PEA, was reviewed and approved by Chad Sorba, P.Geo, Denison's Director Technical Services, and Andy Yackulic, P.Geo, Denison's Director Exploration, each of whom is a Qualified Person in accordance with the requirements of NI 43-101. Technical Reports For further details regarding the Wheeler River project, please refer to the Company's press release dated June 26, 2023 announcing the results of the Phoenix FS and Gryphon PFS Update and the technical report titled "NI 43- 101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" with an effective date of June 23, 2023 ("Wheeler River Technical Report"). For further details regarding the Waterbury Lake project, please refer to the Company's press release dated November 17, 2020 and the technical report titled "Preliminary Economic Assessment for the Tthe Heldeth Túé (J Zone) Deposit, Waterbury Lake Property, Northern Saskatchewan, Canada" with an effective date of October 30, 2020 ("Waterbury PEA"). The PEA is a preliminary analysis of the potential viability of the Project's mineral resources, and should not be considered the same as a Pre-Feasibility or Feasibility Study, as various factors are preliminary in nature. The PEA includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and there is no certainty that the preliminary economic assessment will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability. Scheduled tonnes and grade do not represent an estimate of mineral reserves. For a description of the data verification, assay procedures and the quality assurance program and quality control measures applied by Denison, please see Denison's Annual Information Form dated March 27, 2023. A copy of the foregoing is available on Denison's website and under its profile on SEDAR+ and on EDGAR. 2