#1Corporate Update November 2023 Powering PEOPLE, PARTNERSHIPS AND PASSION. Denison Mines Uranium Development & Exploration The Athabasca Basin, Northern Saskatchewan DML DNN LISTED LISTED TSX NYSE AMERICAN VOLVO#2Cautionary 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#3The Uranium Investment Thesis: Rapid re-alignment of scarce supplies in the face of growing demand 300 250 200 Annual Utility Uranium Requirements (1) (million pounds U30,- per UxC Q1'23) 150 Covered Demand 100 50 2027 Uncovered Demand 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 Key Market Themes: 1. Projected demand for uranium exceeds current supply forecast. (2) Many sources of additional near-term supply require higher prices to justify new mine development. (3) 2. Geopolitical concerns continue to drive nuclear fuel contracting as buyers look to reduce or eliminate Russian exposure. (4) 3. Positive demand outlook for existing reactor fleet, with major government efforts in USA, Japan, and South Korea to preserve several operating reactors and build additional ones. 4. Small modular reactors (SMRS) move closer to deployment, with uranium demand impact potentially beginning in the late 2020s.(5) 5. Supply chain challenges are causing delays and production challenges in the short term at operating mines and brownfield restarts. (6) Lenison NOTES: (1) Data in this slide has been derived from UxC's Uranium Market Outlook dated Q1'2023, including UxC's estimates of uncovered requirements and the URM "Base Demand No Inventory Build" requirements forecast to estimate covered demand. (2) See Ux Weekly 36-42. (3) See TradeTech's Nuclear Market Review, 11/30/22, "In Focus - TradeTech's Production Cost Indicator." (4) See Ux Weekly 36-13, 36-16, and 36-47. (5) OPG currently projects completion of SMR at Darlington by 2028 (LINK). (6) See Ux Weekly 37-12. 3#4Lenison Diversified Athabasca Basin asset base with superior development leverage 95% (1) effective interest in Flagship 62 Wheeler River project Development-stage project Largest undeveloped uranium project in the infrastructure rich eastern Athabasca Basin 2023 Phoenix Feasibility Study(2) Draft Environmental Impact Statement ("EIS") submitted (6) 22.5% interest in Strategic McClean Lake Uranium Mill Strategic regional asset +11% of global uranium production Excess licensed annual capacity Licenced for expansion of tailings management facility ("TMF") (3) 67.41% interest in Emerging Waterbury Lake project PEA stage development project(4) Tthe Heldeth Túé ("THT") deposit (formerly J Zone) highlights potential for future development project pipeline Participating interests in key development- -285,000 stage assets operated by uranium "majors" Includes 22.5% in McClean Lake (Orano), 25.17% in Midwest (Orano), and an effective 15% in Millennium (Cameco) through 50% ownership of JCU(5) hectares of exploration ground PHOTO: Aerial view of Denison's 22.5% owned McClean Lake mill facility NOTES: (1) Denison increased its effective interest in Wheeler River as part of the acquisition of 50% of JCU (Canada) Exploration Company, Limited. See Denison's news release dated August. 3, 2021. (2) See the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. (3) See news release dated January 19, 2022. (4) Refer to the Waterbury Lake Technical Report titled "Preliminary Economic Assessment for the Tthe Heldeth Túé ( Zone) Deposit, Waterbury Lake Property, Northern Saskatchewan, Canada" dated October 30, 2020. (5) See news release dated August. 3, 2021. (6) See news release dated October 26, 2022. 4#5$70.00 $60.00 $50.00 $40.00 All-in / Full Costs - USD$/lb U308 $30.00 $20.00 $10.00 $0.00 ISR Denison's development portfolio projects: Positioned amongst the lowest all-in cost assets of UxC's First Tier Lenison Sample of Global Production Costs - August 2023 (1)(2)(3) Planned and Producing Operations (with Mining Method) UxC's "First Tier" (includes lowest-cost projects with full costs up to ~US$33/lb U₂Og) US$25.47 US$24.93 (2023) (2020) US$16.04 (2023) Akbastau Inkai ISR Phoenix/Wheeler ISR Kharasan ISR Arrow UG UG THT/Waterbury ISR Gryphon/Wheeler UG Olympic Dam Denison/Canada Canada Kazakhstan UG "Third/Fourth Tier" (up to US$92/lb U308) "Second Tier" (up to ~US$48/lb U3O8 McArthur River Cigar Lake UG UG Dasa Honeymoon Australia ISR UG Rabbit Lake U.S.A. Rössing OP OP Husab Goliad Imouaren ISR Africa OP NOTES: (1) Chart data, including "full costs" and UxC's categorization of production cost "tiers", have been derived from UxC's estimates of worldwide production costs from the Uranium Production Cost Study dated August 2023. (2) For Phoenix and Gryphon, see the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. (3) For THT/Waterbury, refer to the Waterbury Lake Technical Report titled "Preliminary Economic Assessment for the Tthe Heldeth Túé (THT) (J Zone) Deposit, Waterbury Lake Property, Northern Saskatchewan, Canada" dated October 30, 2020. 5#6Lenison Robust Balance Sheet with CAD$390M in pro-forma working capital and investments (1, 2) 2.5M lbs U308 in holdings of physical uranium ~CAD$13.2M EXIT investments in Market value ~CAD$248M (US$73.50/lb U308) Acquired at average cost of USD$29.66/lb U308 Long-term holding expected to enhance access to future project financing for flagship Wheeler River(3) All material received and held in licenced North American storage facilities (Cameco + ConverDyn) Reported sale of 200K lbs U3Og for delivery in Q4'2023 at average price of USD$73.38 uranium equities Significant equity holdings in uranium exploration and development companies, including Skyharbour Resources Ltd. & GoviEx Uranium Inc. At-The-Market (ATM) (4) facility provided opportunistic and low-cost access to capital through base-shelf prospectus. 19.8M common shares issued in 2023 at an average price of CAD$1.91 per share(5) ~CAD$60.8M in cash and cash equivalents at September 30, 2023 412 g 3144 PHOTO: Packaged U30g yellowcake at Denison's 22.5% owned McClean Lake mill. NOTES: (1) As of September 30, 2023, for additional details see financial statements and MD&A for the period ended September 30, 2023; excludes investment in joint venture (ICU). (2) Pro-forma adjustment includes addition of ~CAD$71M in estimated net proceeds from equity financing completed in October. See Denison's news release dated October 16, 2023. (3) See Denison's news releases dated March 15, 2021, March 22, 2021, and April 1, 2021. (4) See Denison's news release dated September 28, 2021. (5) As of September 30, 2023, for additional details see financial statements and MD&A for the period ended September 30, 2023. 6#7Environmental, Social, Governance & Indigenous (ESG+I) Fundamental considerations driving Denison's operations Sakitawa Ellen Grap Lodge Powering PEOPLE, PARTNERSHIPS Multiple Indigenous Agreements In Place AND PASSION. Denison Mines www.denisonmines.com Shared Prosperity Agreement with English River First Nation (2) Participation/Funding and/or Exploration Agreements with: Kineepik Métis Local / Pinehouse (3), Ya'thi Néné Lands & Resources Office (4), and Métis Nation Saskatchewan (5) Comprehensive ESG Reporting Designed to address GRI, SASB, TCFD and other global disclosure frameworks Board approved Indigenous Peoples Policy |First-in-sector policy reflecting Denison's commitment to take action towards advancing reconciliation with Indigenous peoples in Canada (1) Strong EHS&S Culture & Results Zero lost time injuries across all operations and no significant environmental events for 2022(8) | | Top 125 in Canada Leading Governance Practices & Disclosure Denison recognized by Globe & Mail "Board Games" as top | uranium development | company for corporate governance practices & disclosure in its assessment of leading companies and trusts included in Canada's | benchmark S&P/TSX | Composite Index(6, 7) Authentic Social Programs Denison's community/ social investment program targets community-based initiatives Lenison PHOTO: Highlights of the Elders of Sakitawak's market garden in Ile a la Crosse, a community-based initiative sponsored by Denison. LINKS: Denison's ESG Report ERFN SPA Signing Video NOTES: (1) See news release dated December 2, 2021. (2) See news release dated September 27, 2023. (3) See news release dated June 23, 2022. (4) See news release dated October 20, 2022. (5) See MD&A for the period ended Dec. 31, 2022 (6) For more information: https://www.theglobeandmail. com/business/careers/manag ement/board-games/article- the-globe-and-mails- comprehensive-ranking-of- canadas-corporate-boards-2/ (7) See Denison's news release dated March 15, 2021. (8) See Denison's 2022 Annual Information Form for additional details. 7#8Large land position in the infrastructure-rich eastern portion of the Athabasca Basin (1)(2) Northwest Territories ATHABASCA ATHABASCA BASIN Midwest (Denison 25.17%) Alberta Saskatchewan Manitoba Prince Alber Saskatoon Regina 100% Denison Denison operated JV Orano operated JV Cameco operated JV Denison earn-in Uranium mines and deposits Uranium mill Roads Powerlines Waterfound (Denison 24.68%) (3) Arrow Triple R Hook-Carter A 50 km Waterbury Lake (Denison 67.41%) Hatc ake -Waterfound North Bell Lake Mur Wolly Waterfound- Waterbury Lenison J Zone Roughrider Turkey Lake McClean Lake Mill (Denison 22.5%) McClean Lake Mill Eagle Point McClean Lake (1) Denison direct land position shown as of September 30, 2023. Johnston Lake Cigar Lake Midwest ab Rabbit Lake Mill NOTES: Packrat Candle Darby Cigar Lake Mine Park Creek Epp Lake -West Bear Marten Wolverine McArthur River Mine IVE Mann Lake Lynx Moon Lake South 父 (Denison 75%) Centennial Moon Lake North Moon Lake South' Moon Lake nnium Bachman Lake Wheeler River (Phoenix & Gryphon deposits) Russell Lake Wheeler River (Denison 95%)(3) Ford Lake Crawford Lake Provincial Power Grid All Season Highway/Haul Road Brown Lake Key Lake Mill (2) Excludes interests held only through 50% ownership of JCU - See Denison news release dated August 3, 2021. (3) Reflects Denison's effective interest, including a portion attributable to Denison's 50% ownership in JCU (Canada) Exploration Company, Limited. See Denison's news release dated August. 3, 2021. 8#995% owned flagship Wheeler River development project(1)(2) Two Low-cost development assets Phoenix - designed as a low- cost In-Situ Recovery ("ISR") operation with on-site processing to finished yellow cake (U308) Gryphon - contributes additional low-cost production via conventional underground mining with assumed toll milling at 22.5% Denison owned McClean Lake mill ~16.5 years Aggregate operating Mine life(3) 106.4M lbs U308 combined Proven & Probable Reserves (100% basis) Atlas Copco CAD$419M Estimated (100% basis) Initial CAPEX (Phoenix) 2023 Costing in NI 43-101 compliant Phoenix Feasibility Study and Gryphon PFS Update reflect current post-inflation costing environment Located within the boundaries of Treaty 10 in the traditional territory of English River First Nation, in the homeland of the Métis, and within Nuhenéné 11,720 hectares of prospective ground over 19 claims 49,000kg Sa Kerr Lenison PHOTO: Installation of large- diameter commercial scale ISR test wells at Phoenix during 2021. LINKS: Wheeler River Project Page on Denison Website NOTES: (1) Refer to the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. (2) Denison increased its effective interest in Wheeler River as part of the acquisition of 50% of JCU (Canada) Exploration Company, Limited. See Denison's news release dated August 3, 2021. (3) Reflects 10-year mine life estimated for Phoenix and 6.5-year mine life estimated for Gryphon. 9#10Phoenix In-Situ Recovery ("ISR") Feasibility Study (2023): Reflects rigour of multi-year technical de-risking and delivers impressive economic results (1) i c$1.56B estimated 70.5M lbs U₂Og @ 11.4% U308 | post-tax NPV, (100% basis) 8% Measured & Indicated Mineral Resources (280,200 tonnes, 100% basis) One of the highest- grade undeveloped uranium deposits globally Including... 56.3M lbs U₂Og @ 46.0% U308 M&I mineral resources for Zone A high-grade domain | Base-case (see note 3, 4) i 90.0% estimated Base-case | post-tax | IRR (see note 3, 4) US$6.28 / lbs U308 | average Cash Operating Costs | (C$8.51/lb U308) i c$419M estimated Initial | CAPEX (100% basis) i 3.7 to 1 impressive | Base-case | post-tax NPV |to initial capital | cost ratio US$16.04 / lbs U308 | average All-in Cost (2) | (C$21.73/lb U308) Lenison PHOTOS: Phoenix Feasibility Field Test (FFT) facilities during operations in 2022. NOTES: (1) See the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. (2) All-in cost is estimated on a pre-tax basis and includes all project operating costs, capital costs post-FID, and decommissioning costs divided by the estimated number of pounds U308 to be produced. (3) NPV and IRR are calculated to the start of construction activities for the Phoenix operation, and excludes $67.4 million in pre-FID expenditures. (4) Post-tax NPV, IRR and payback period are based on the "adjusted Post-tax" scenario, which includes the benefit of entity level tax attributes which are expected to be available and used to reduce taxable income from the Phoenix operation. See Wheeler River Technical Report for details. 10#11Phoenix ISR Feasibility Study (2023)(1): Optimized production profile based on detailed ISR mine planning efforts Denison Phoenix mine production per year by phase 10,000,000 Pounds U3O8 per year 9,000,000 8,000,000 7,000,000 6,000,000 5,000,000 4,000,000 3,000,000 2,000,000 1,000,000 Robust economics Phase 1 Phase 2 Phase 3 Phase 4 Phase 5 easily absorb cost-inflation + design changes ~10-month payback period for pre- and post- tax base-case scenarios 56.7 million lbs U3Og in proven and probable reserves (219,000 tonnes at 11.7% U308) Assumptions / Results(1) Base Case PFS Ref. Selling price/lb U308 US$66-US$70 US$65 USD:CAD FX Rate 1.35 1.3 Pre-tax NPV 8% (2)(4) (100%) $2.34 billion $2.05 billion Calendar Years Production Lbs U₂Os 1 2 3 4 5 6 7 8 9 10 11 Change from 2018 PFS +150% +5% 4.0M 9.2M 9.2M 9.0M 8.0M 5.0M 5.0M 3.2M 2.5M 1.1M 0.5M Pre-tax payback period (3)(5) ~10 months ~10 months NOTES: (1) Refer to the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023; (2) NPV and IRR are calculated to the start of construction activities for the Phoenix operation, and excludes $67.4 million in pre-FID expenditures; (3) Payback period is stated as number of months to payback from the start of uranium production; (4) Post-tax NPV is estimated to be $1.43 billion ($1.56 billion adjusted) in the base-case and $1.26 billion ($1.38 billion adjusted) in the PFS Reference Case; (5) Post-tax payback period is estimated to be 11 months (10 months adjusted) in the Base-Case and 12 months (11 months adjusted) in the PFS Reference Case; (6) Post-tax IRR is estimated to be 82.3% (90.0% adjusted) in the Base-Case and 76.4% (83.9% adjusted) in the PFS Reference Case. Pre-tax IRR(2)(6) 105.9% 98.4% 11#12Denison Mines Phoenix ISR Freeze Wall: Isometric View at Ore Level Unconformity C Phase 5 Phoenix Zone B Phoenix Zone A Phase 1 Phase 2 Phase 3 Phase 4 D N Phoenix Zone B2 Phoenix Zone B1 750 m Notes: Isometric view centered at 400 m depth below ground surface (ore level) • Window 35 m above and below the ore zone level ⚫Frozen cross walls are thawed as freeze wall expands to accommodate subsequent phases Robust mine Freeze Wall (No planning process evaluation of production potential for individual well patterns: 74 extraction, 172 injection, and 22 monitoring wells Mineralized Zone Footprint MINING PHASE 1 MINING PHASE 2 Freeze Wall Mineralized Zone Footprint (No Flow Boundary) MINING PHASE 3 Extraction Well Injection Well (large diameter) Injection Well (narrow diameter) Injection Well (exploration borehole) N637 4500 N6375000 N 27 N04000 (28) N6323500 7.2 (7.3) 38) 16 26 LEGEND: FREEZE WALL OUTLINE NEW SITE FEATURE FUTURE 10 120m SHORELINE 540 CONTOUR ORE BODY FEATURE ITEM NO. 20 -124 (12) $2 125 17 10: (103) 10.1 Environmental disturbance limited by compact site Primary site facilities contained within area estimated to be less than 1 sq. km (31) (25) Om 100 200 300 400 500 1:10000 Item Description 1 ISR Well Field 2 Freeze Plant 3 ISR Plant 4 Contaminated Runoff Pond and Pumphouse 5 Process Precipitates Solids Pad 6.1 Gypsum Waste Pond 6.2 Gypsum Waste Pond (Future) 7.1 Industrial Landfill 7.2 Industrial Leachate Collection Pond 7.3 Industrial Landfill (Future) 8 Special Waste Pad 9.1 Clean Waste Pad 9.2 Clean Waste Runoff Pond Effluent Monitoring and Release Pond and Pumphouse 10.1 Effluent Monitoring and Release Pond Effluent Monitoring and Release Pond Lenison Phoenix Feasibility Study: Expected to provide an excellent basis to advance engineering designs in support of a future final investment decision 10.2 10.3 11 Process Water Pond and Pumphouse 12 Industrial Waste Water Treatment Plant 13 Wash Bay/Scanning Facility 14 Propane Storage (1 Camp, 1 Mill) 15 Potable Water Plant 16 Camp 17 Standby Diesel Generator (2) 18 138kV Substation Yard N ROAD ALIGNMENT ADJUSTMENT AIRPORT CHANNEL CROSSING APRON 19 Operations Centre, Gate House 20 Plant Support Facilities 21 Covered Storage 22 Fenced Storage 23 Hazardous Storage Short Term Storage Pad RUNWAY 24 Potable Water Tank and Pumphouse (41) 25 Fire Water Tank and Pumphouse 26 Fuel Storage 27 Monitoring Wells 28 Fresh Water Wells (Quantity of 2) 29 (Intentionally Blank) 30 Lake Water Intake THIS DRAWING 31 Lake Water Discharge 32 UBS Settling Pond PROPOSED ACCESS (34) 33 OVERHEAD ROAD TO SITE POWER LINE (33) EXISTING OVERHEAD POWER LINE HWY 914 34 35 Domestic Wastewater Treatment Facility 36 (Intentionally Blank) 37 Main Electrical Switch room 38 Diesel Fuel Storage Tank 39 SaskPower 138kV Overhead Power Line 40 Transformers (2) 41 Airport (See Key Plan) KEY PLAN 42 Communication Tower Domestic Landfill (See Key Plan) Construction Waste Laydown Area (See Key Plan) NOTES: (1) Refer to the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Can ada" dated June 23, 2023. 12#13Phoenix ISR De-Risking: Combining the world's lowest cost uranium mining method with one of the world's highest-grade undeveloped uranium deposits Lenison 2019/2020 ISR Field Tests (1) 35 small-diameter test, observation and re- charge wells 2 large-diameter commercial scale wells Pump and injection tests collecting critical hydrogeological data Demonstrated "Proof of Concept" for use of ISR Specialized Core Leach Testing Leach testing indicative of in-situ conditions using intact core samples from Phoenix Results consistently produced uranium bearing solution head- grade levels significantly higher than grade used in the 2018 PFS(2) +97% recovery achieved during long-term test(5) CAN BE SC999 Additional High- Grade uranium discovered at Phoenix(3) 22.0% eU308 over 8.6 metres in GWR-045 Located outside of the existing high-grade resource domain for Zone A and Phase 1 of the current mining plan 2021 field test of commercial-scale ISR test pattern(4) Achieved commercial- scale flow-rate used in the 2018 PFS Completed Athabasca Basin's first "tracer test" showing hydraulic control, breakthrough times consistent with modelling, and ability to carry out "clean-up" PHOTOS (Left to Right): Small diameter ISR test wells installed at Phoenix in 2019; Specialized core- leach testing apparatus from the Saskatchewan Research Council (SRC); high-grade uranium core and scintillometer; monitoring of commercial scale ISR test wells at Phoenix in 2021. LINKS: 2021 Phoenix ISR Test Program on Vimeo NOTES: (1) See Denison's news releases dated December 18, 2019, February 24, 2020, and June 4, 2020. (2) See Denison's news releases dated February 19, 2020, and August 4, 2021. (3) See Denison's news release dated July 29, 2021. (4) See Denison's news release dated October 28, 2021. (5) See Denison's news release dated December 8, 2022. 13#14Fully Permitted In-Situ Recovery Feasibility Field Test (FFT): Highly successful first-of-its-kind test in the Athabasca Basin (1, 2) Double Walled Pipe to Recharge Well Lenison CAUTION The Phoenix FFT was designed to validate and inform various Feasibility Study (FS) elements for use of In-Situ Recovery (ISR) mining, including production and remediation profiles, and is planned to occur in three phases. The first two phases supported 2023 Phoenix FS. Leaching Completed successful injection of acidic solution and recovery of uranium bearing solution using a portion of the test | pattern installed at Phoenix in 2021(3). Neutralization Completed successful injection of mild alkaline solution to reverse the leaching process and return test area to protective conditions(4). Recovered Solution Management Completed compliance phase to separate recovered solution into mineralized precipitates | (temporarily stored on site) and neutralized treated solution (injected into sub-surface)(5). Test Wells Injection Solution Preparation Module -2-Trailers Recovered Solution Management Modules Mineralized- Precipitate Storage -03 OWR-040 ww-041 Washcar/Dry Trailer -Containment Berms Tanker Pad Recovered Solution Surge Tank -Double Walled Transfer Piping Perimeter Fence 6-Outdoor Solution Storage Tanks Solution Storage Area Graded Footprint 10 20 30 40 50m Containment Berms PHOTO: Inside FFT coverall structure during commissioning - including view of commercial scale test wells, monitoring wells, and injection solution preparation module (left) and plan map of Phoenix FFT site (right). NOTES: (1) See Denison's news release dated July 12, 2022. (2) See Denison's news release dated August 8, 2022. (3) See Denison's news release dated October 17, 2022. (4) See Denison's news release dated December 12, 2022. (5) See Denison's news release dated November 2, 2023. 14#15Gryphon UG Pre-Feasibility Study Update (2023)(1): Capital and operating costs updated from 2018 PFS + minor scheduling optimizations 10,000,000 9,000,000 Gryphon mine production per year Benefits from existing or planned Denison-owned infrastructure Denison Payback period under 2-years for pre- and post- tax base-case scenarios Pounds U3O8 per year 8,000,000 7,000,000 6,000,000 5,000,000 4,000,000 3,000,000 2,000,000 1,000,000 49.7 million lbs U3Og in probable reserves 8 (1,275,000 tonnes at 1.8% U3O8) Assumptions / Results(1) Selling price/lb U308 Base Case PFS Ref. US$75 US$65 USD:CAD FX Rate 1.35 1.3 Calendar Years 1 2 3 4 5 6 7 3.2M 5.9M Production Lbs U₂Os NOTES: (1) Refer to the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023; (2) NPV and IRR are calculated to the start of construction activities for the Gryphon operation, and excludes $56.5 million in pre-FID expenditures; (3) Payback period is stated as number of months to payback from the start of uranium production; (4) Post-tax NPV is estimated to be $864.2 million in the base-case and $599.9 million in the PFS Reference Case; (5) Post-tax payback period is estimated to be 23 months in the Base-Case and 26 months in the PFS Reference Case; (6) Post-tax IRR is estimated to be 37.6% in the Base-Case and 30.6% in the PFS Reference Case. 9.0M 9.0M 9.0M 9.0M 4.7M Pre-tax NPV8%(2)(4) (100%) Change from 2018 PFS Pre-tax payback period (3)(5) $1.43 billion $1.00 billion +148% -5% ~20 months ~24 months Pre-tax IRR(2)(6) 41.4% I 34.0% 15#16Gryphon Underground ("UG") Pre-Feasibility Study Update (2023): Provides Denison with additional source of low-cost production to deploy Phoenix cash flows (1) 61.9M lbs U3O8 C$864M estimated Base-case @ 1.7% U308 | after-tax NPV (100% basis) 8% Indicated Mineral Resources (1,643,000 tonnes, 100% basis) Moderate grade allows low-cost conventional UG mining approach Plus... 1.9M lbs U₂O8 Inferred mineral resources (73,000 tonnes @ 1.2% U308, 100% basis) (see note 3, 4) 37.6% estimated Base-case after-tax IRR (see note 3, 4) US$12.75 / lbs U3O8 average Cash Operating Costs | (C$17.27/lb U308) c$737M estimated Initial CAPEX (100% basis) 2023 PFS Update Scope limited to cost update and minor schedule optimization US$25.47 /lbs U₂Og average All-in Cost(2) (C$34.50/lb U308) Lenison PHOTO: View inside the SX circuit at Denison's 22.5% owned McClean Lake mill, which is assumed to toll mill production from the Gryphon UG operation NOTES: (1) See the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. (2) All-in cost is estimated on a pre-tax basis and includes all project operating costs, capital costs post-FID, and decommissioning costs divided by the estimated number of pounds U₂Og to be produced. (3) NPV and IRR are calculated based on assessed "high-case" uranium price, to the start of pre-production activities for the Gryphon operation. (4) Indicative post-tax results were prepared on a combined basis with the Phoenix deposit for Denison's then 90% ownership interest, see slide 12 for details. 16#1767.41% owned Waterbury Lake project demonstrates potential for ISR to transform portfolio projects(1) McClean Lake Mill Access Deniso territo Power ISR im Area sion Line Mining Method Tthe Heldeth Túé (“THT”) deposit (formerly J Zone) designed as a low-cost In-Situ Recovery ("ISR") operation with freeze wall design Uranium Bearing Solutionst Project ("UBS") to be transported by enison truck to 22.5% Denison's owned McClean Lake mill for toll processing Minimal site infrastructure Successful 2023 ISR field test(3) 6-year Mine Life 9.7M lbs U308 (Rio Tinto) CAD$112M estimated Initial CAPEX (100% basis) NI 43-101 compliant projected Preliminary Economic Mine Production North Lan Assessment ("PEA") (100% basis) Airport and Lod completed in 2020(2) 12.8M lbs U308 @ 2.0% U308 (291,00 tonnes) in Indicated Mineral Resources estimated for THT (100% basis) Existing Powerline Located within the boundaries of Treaty 10 in Nuhenéné / Athabasca Denesųłiné traditional territory Aditiona and the homeland of the Métis the homeland of the Métis. Partnership with consortium led by state- owned nuclear company Korea Hydro Nuclear Power ("KHNP") 40,256 hectares of prospective ground over 13 claims Lenison PHOTO: Isometric schematic of ISR wellfield and freeze wall at depth of the THT deposit on Waterbury Lake property. LINKS: Waterbury Lake Project Video on Vimeo Waterbury Project Page on Denison Website NOTES: (1) Refer to the Waterbury Lake Technical Report titled "Preliminary Economic Assessment for McClean Lake the Tthe Heldeth Túé (Zone) Deposit, (Orano/Denis Waterbury Lake Property, Northern Saskatchewan, Canada" and dated October 30, 2020. (2) 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. There is no certainty that the results from the PEA will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability. (3) See Denison's news release dated Nov. 6, 2023 17#18Tthe Heldeth Túé ("THT") ISR Operation: PEA (2020) shows potential for ISR to change uranium mining landscape in Canada (1) Uranium-Bearing Solution Storage Loading Station 1.6M lbs lbs U3O8 Reagent Solution Receiving/Storage ISR Well Field Monitoring Wells Average annual production over 6 years (100% basis) US$12.23 / lbs U308 average Cash Operating Costs (C$16.27/lb U30) C$265M estimated Pre-Tax NPV, (100% basis) US$65/lb U308 selling price (see note 3, 4) 8% i c$112M | estimated | Initial | CAPEX | (100% basis) US$24.93 /lbs U3O8 average All-in Cost(2) (C$33.16/lb U308) | 50.0% estimated Pre-Tax IRR | US$65/lb U308 selling price | (see note 3, 5) Lenison PHOTOS: Aerial rendering of surface facilities for the THT ISR operation NOTES: (1) Refer to the Waterbury Lake Technical Report titled "Preliminary Economic Assessment for the Tthe Heldeth Túé ( Zone) Deposit, Waterbury Lake Property, Northern Saskatchewan, Canada" dated October 30, 2020. See PEA note on Slide 15. (2) All-in cost is estimated on a pre-tax basis and includes all project operating costs and capital costs divided by the estimated number of finished pounds U308 produced. (3) NPV and IRR are calculated based on assessed "high-case" uranium price, to the start of pre-production activities. (4) Post-tax NPV attributable to Denison's then 66.90% interest is estimated to be between $72 million (base-case) and $109 million ($65/lb high-case). (5) Post-tax IRR attributable to Denison's then 66.90% interest is estimated to be between 30.4% (base-case) and 38.9% ($65/lb high-case). 18#1922.5% Denison-owned McClean Lake Mill Operation: Excess licensed capacity and CNSC approval in place for expansion of tailings facility +14% of global uranium production 2022 operating production of ~18M lbs U308 from Cigar Lake under tolling agreement, represents ~14% of UxC's estimated global primary production for 2022(1) 750km north of Saskatoon (4) Accessible by road over all-weather highways and by air via Points North 24M 6M lbs U308 1 lbs U₂Og Licensed annual production (4) 10-Year CNSC Operating License(4) Renewed in 2017 for operations up to June 30, 2027 +50M lbs U3O8 Historic uranium production from | mined McClean Lake deposits (JEB | Excess licensed capacity if 18M lbs U308 produced under Cigar Lake tolling(2) Orano Canada Inc. French nuclear | giant serves as site | operator and is | owner of 77.5% interest TMF Expansion Approved (3) CNSC approval obtained to increase tailings + Sue A, B, C, & E) (4) | capacity Lenison PHOTO: Aerial view of Denison's 22.5% owned McClean Lake mill facility LINKS: McClean Lake Project Page on Denison Website NOTES: (1) Per UxC's Q1'2023 Uranium Market Outlook. (2) Denison monetized its share of tolling revenues from the Cigar Lake toll milling agreement. See Denison's news releases dated February 1, 2017 and February 13, 2017. Please also refer to Denison's current Annual Information Form and Financial Statements and Management, Discussion and Analysis for additional details related to the toll milling agreement. (3) See Denison's news release dated January 19, 2022. (4) See Denison's current Annual Information Form for additional details regarding the McClean Lake mill facility. 19#2022.5% Denison-owned McClean Lake Property: SABRE mining method has potential to unlock value from unmined deposits close to mill SABRE mining Patented SABRE mining method Successful 5-year test mining program for "Surface Access Borehole Resource Extraction" (SABRE) mining method Mined four cavities of McClean North deposit in 2021 to produce -1,500 tonnes of high- value ore (1) Orano Canada Inc. French nuclear giant serves as project operator and is owner of 77.5% interest method is property of | McClean Lake JV | with patent issued in 2016 17.8M lbs U₂Og Indicated Mineral Resources(2) (100% basis) Combined 374,900 tonnes @ 2.22% U308 for the Caribou, Sue D and McClean North deposits | 4,258 Hectares 4 mineral leases (1,147 hectares) plus 13 mineral claims (3,111 hectares) To Evaluate The use of the SABRE mining method for use on unmined McClean Lake deposits(1) 7.6M lbs U₂Og Inferred Mineral Resources (2) (100% basis) Combined 510,900 tonnes @ 0.68% U308 | for the Sue D, Sue E, and McClean North deposits T 8.67% U30% | over 13.5 metres Discovered "new" mineralization at | McClean South(3) in 2021 + expanded footprint in 2022(4) Lenison PHOTO: 2021 SABRE test mining program in action, with view of specialized mining pipes in inset photo. LINKS: McClean Lake Project Page on Denison Website NOTES: (1) See Denison's news release dated November 3, 2021. (2) See Denison's current Annual Information Form for additional details regarding the McClean Lake deposits and SABRE mining method. (3) See Denison's current Annual Information Form. (4) See Denison's news release dated September 8, 2022. 20#2125.17% Denison-owned Midwest Property: Two high-grade uranium deposits in close proximity to the McClean Lake mill Approved ISR Concept Environmental | Study Impact Statement (“EIS”) Despite deferral of development decision in 2008, EIS approval efforts continued with assessment of open pit mining method and processing at McClean Lake. CNSC approved final EIS in 2012(1) 25km from McClean Lake mill Via existing roads, and only 1km from the Points North airstrip Positive results support joint venture decision to complete additional ISR | studies and potential PEA(3) Midwest I Main deposit(2) Orano Canada Inc. French nuclear giant serves as project operator | and is owner of 74.83% interest Midwest "A" deposit(2) | 10.8M lbs U308 | (453,000 tonnes @ | (566,000 tonnes @ | 39.9M lbs U₂O 4.0% U308) in Indicated Mineral Resources 11.5M lbs U308 (793,000 tonnes @ 0.66% U30g) in Inferred Mineral Resources (100% basis) 0.87% U30g) in Indicated Mineral Resources | 6.7M lbs U308 (53,000 tonnes 5.8% U30g) in Inferred Mineral Resources (100% basis) Lenison PHOTO: Aerial view of Midwest Project. LINKS: Midwest Project Page on Denison Website NOTES: (1) See Denison's current Annual Information Form for additional details regarding the Midwest project. (2) Refer to the Midwest Technical Report titled "Technical Report with an Updated Mineral Resource Estimate for the Midwest Property, Northern Saskatchewan, Canada" and dated March 26, 2018. (3) See Denison's news release dated April 12, 2023. 21#22Reserves & Resources as of June 26, 2023. Mineral Reserves Denison Share(9) Denison Share(9) Lbs U308 (,000) 100% Basis (see Notes 1, 2, 3, 4, 14, 15) Inferred Mineral Resources (see Notes 1, 6, 15) 100% Basis Project/Deposit Tonnes Grade Lbs U308 % U308 (,000) Lbs U308 (,000) Project/Deposit Tonnes Grade % U308 Lbs U308 (,000) McClean Ore Stockpile (Proven) Wheeler River - Phoenix (Proven) Wheeler River - Phoenix (Probable) Wheeler River - Gryphon (Probable) Total Proven & Probable Reserves 90,000 0.37 700 6,300 212,700 1,257,000 1,566,000 24.5 3,400 11.4 53,300 200 3,200 50,600 Wheeler River - Phoenix(7) 5,600 2.6 300 300 Wheeler River - Gryphon (7) 73,000 1.2 1,900 1,800 McClean Caribou 24,200 0.39 200 0 1.8 49,700 47,200 McClean Sue D 483,400 0.69 7,300 1,600 107,100 101,200 McClean McClean North 3,300 0.79 100 0 Midwest - Midwest Main 793,000 0.66 11,500 2,900 Measured & Indicated Mineral Resources (see Notes 1, 5, 15) Project/Deposit Denison 100% Basis Midwest Midwest A 53,000 5.8 6,700 1,700 Share (9) Waterbury - Huskie 268,000 0.96 5,700 3,800 Tonnes Grade % U308 Lbs U308 (,000) Lbs U308 Christie Lake(13) (,000) Total Inferred Resources 588,000 2,291,500 1.57 20,400 3,500 54,100 15,600 Wheeler River - Phoenix(7) (Measured) Wheeler River - Phoenix (7) (Indicated) Wheeler River - Gryphon (7) (Indicated) 64,200 21.8 30,900 29,400 216,000 8.3 39,700 37,700 100% Basis 1,643,000 1.7 61,900 58,800 (see Notes 15, 16) McClean Caribou (Indicated) McClean Sue D (Indicated) 47,800 2.6 2,800 600 Project/Deposit Tonnes Grade % U308 Lbs U308 (,000) (,000) 122,800 1.1 2,800 600 Millennium Indicated (11) McClean McClean North (Indicated) 204,300 2.8 12,200 2,700 Kiggavik - Indicated (12) 1,442,600 10,418,000 2.39 75,900 11,400 0.47 127,300 21,500 Midwest Midwest Main (Indicated) 453,000 4.0 39,900 10,100 Tot. Historic Indicated Resources Midwest Midwest A (Indicated) Waterbury - THT (Indicated) Total Measured & Indicated 566,000 291,000 3,608,100 0.87 10,800 2,700 Millennium - Inferred (11) 2.0 12,800 213,800 8,600 Kiggavik - Inferred (12) 11,860,600 412,400 731,000 3.19 0.28 203,200 29,000 5,400 32,900 4,400 900 151,200 Resources Tot. Historic Inferred Resources 1,143,400 34,400 5,300 Historic Mineral Resources Denison Share(10) Lbs U308 Notes cont'd: (6) See AIF or June 26, 2023 news release, as applicable, for details of the cut-off grades used for the inferred mineral resources. (7) Measured & Indicated mineral resources for Phoenix and Gryphon deposits are inclusive of mineral reserves. (8) The operator conducted confirmatory drilling on a portion of the Sue E mineral resources outside the designated pit and late in 2006 submitted a preliminary analysis detailing an inferred mineral resource of approximately 2 million pounds on a 100% basis in this area, as compared to the 7.3 million pounds that Scott Wilson Roscoe Postle Associates Inc. ("Scott Wilson RPA", succeeded by Roscoe Postle Associates Inc. ("RPA") and then acquired by SLR Consulting Limited, "SLR"), estimated in its February 2006 technical report. The mineral resource has not been re-estimated using the new drill information. (9) Reflects an effective 95.00% interest in the Wheeler River project, a 22.50% interest in the McClean Lake property; a 25.17% interest in the Midwest project; and a 67.41% interest in the Waterbury Lake property pursuant to the terms of the agreements with its applicable joint venture partners. (10) Denison's share has been calculated as 50% of the product of JCU's percentage interest in the applicable project multiplied by the estimated mineral resources on a 100% basis. (11) Millennium mineral resources as reported by Cameco on their website at https://www.cameco.com/businesses/uranium-projects/millennium/reserves-resources. Cut-off grades and other assumptions, parameters and methods used to estimate resources are unknown. (12) Kiggavik mineral resources as reported by Orano in their 2020 Activities Report available on their website at https://www.orano.group/docs/default-source/orano-doc/groupe/publications-reference/publication-groupe/orano_annual-activity-report_2020_online.pdf?sfvrsn=b8263a0d_27 and converted from tonnes U to pounds U308 and from %U to %U308. Cut-off grades and other assumptions, parameters and methods used to estimate resources are unknown. (13) Christie Lake mineral resources, and relevant assumptions, parameters and methods used for estimating, are documented in the "Technical Report for the Christie Lake Uranium Project, Saskatchewan, Canada" with an effective date of December 31, 2021 and filed under the Company's profile on SEDAR and EDGAR on March 27, 2023. The Christie Lake mineral resources were estimated at a cut-off grade of 0.2% U308. (14) The summary information on Denison's proven mineral reserve estimates for McClean Lake was prepared from the year-end stockpile survey reported by Orano Canada, the MLJV operator. (15) Numbers may not add due to rounding. (16) A qualified person has not done sufficient work to verify and classify these historical estimates as current mineral resources for the Company or confirm their reporting of resources is in accordance with NI 43-101 categories. See AIF for details. Lenison SOURCE: For Wheeler River, see the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Canada" dated June 23, 2023. For all other projects, see Denison's Annual Information Form dated March 27, 2023 NOTES: (1) CIM definitions were followed for classification of mineral reserves and mineral resources. Mineral resources are not mineral reserves and do not have demonstrated economic viability. (2) Mineral reserves for the Phoenix deposit are estimated at a cut-off grade of 0.5% U308 based on the ISR mining method, using a long- term uranium price of USD$50/lb U308 and a USD$/CAD$ exchange rate of 1.33. The mineral reserves are based on a mine operating cost of $0.78/lb U308, process operating cost of $5.20/lb U308, and process recovery of 99%. (3) Mineral Reserves for the Gryphon deposit are estimated at a cut-off grade of 0.58% U308 based on longhole mining using a long- term uranium price of USD$50/lb and a USD$/CA$ exchange rate of 0.80. The mineral reserves are based on a mine operating cost of $150/t, mill operating cost of $275/t, G&A cost of $99/t, transportation cost of $50/t, milling recovery of 97%, and 7.25% fee for Saskatchewan royalties. Mineral reserves estimates account for diluting material and mining losses. (4) Mineral reserves are stated at a processing plant feed reference point and include diluting material and mining losses. (5) See AIF or June 26, 2023 news release, as applicable, for details of the various cut-off grades used for measured & indicated mineral resources. 22#23Capital Structure & Corporate Information Market Summary(1) Management Exchanges Shares Outstanding Share Purchase Warrants Shareholders(4) TSX: DML NYSE American: DNN 888.6 M David Cates (President & CEO, Director) Elizabeth Sidle (VP Finance, Interim CFO) Kevin Himbeault (VP Operations & Reg. Affairs) Amanda Willett (VP Legal) 40% 52% Share Units 6.9 M Options 6.8 M Fully Diluted Shares 902.2 M DML (TSX) Market Cap @ C$2.22/share(2) CAD $1.97 B Daily Trading Volume(3) 2.1 M Shares DNN (NYSE American) Market Cap @ US$1.62/share(2) USD $1.44 B Daily Trading Volume (3) 8.6M Shares David Bronkhorst (Technical Advisor) Denison DML LISTED TSX DNN LISTED NYSE AMERICAN Board of Directors Ron Hochstein (Non-Executive Chair) Brian Edgar (Lead Director) Byeong Min An (KHNP Nominee) David Cates (President & CEO, Director) David Neuburger Laurie Sterritt Jennifer Traub Patricia Volker 8% ■ Institutional Insiders ■ Other (4) Shareholder information is estimated as of May 25, 2023. Information is provided for indicative purposes only. Institutional holdings are estimated based on information available on Bloomberg. Insider holdings are estimated based on applicable filings and includes estimated holdings from entities entitled to appoint a nominee to the Board of Directors. Other holdings are determined as shares outstanding less those reported as institutional and insider holdings. Share ownership is subject to change. LINKS: Website: www.denisonmines.com Twitter: @DenisonMinesCo Email: [email protected] NOTES: (1) Share capital information as of November 8, 2023 (Q3'2023 MDA). (2) Based on shares outstanding at November 8, 2023 (Q3'2023 MDA) and DML/DNN share prices as of the end of October 2023. (3) Average daily trading volume over previous 3 months as of the end of October 2023. 23