Denison Mines : Investor Update - March 2024

Corporate Update

March 2024

Uranium Development & Exploration

The Athabasca Basin, Northern Saskatchewan

Cautionary Statements & References

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-lookingstatements can be identified by the use of forward-lookingterminology 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 River; 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-lookinginformation 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-lookingevents, please refer to the "Risk Factors" in the Management Discussion & Analysis dated February 29, 2024 available under its profile on SEDAR+ at www.sedarplus.ca and 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-lookingstatements. 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, Vice President Technical Services & Project Evaluation, and Andy Yackulic, P.Geo, Vice President 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-Feasibilityor 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.

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Key Investment Highlights(1):

Advanced Athabasca Basin uranium developer with unique asset mix

Threelow-cost uranium development projects operated by Denison

Phoenix, Gryphon, and THT/Waterbury all within UxC's "First Tier" of global assets

Phoenix combines lowest-cost mining method with Athabasca Basin high-grades

Flagship ISR project advancing through permitting with significant technical de-risking complete

Interest in strategic regional asset with McClean Lake mill and mine

Excess licensed milling capacity with approval for expanded tailings management facility

2025 mining restartat McClean Lake North deposit with planned initial prod'n of 800,000 lbs U3O8 (100%)

High-potential exploration portfolio and interests in key mines / projects operated by "majors"

Large exploration portfolio, including Moon Lake South and Johnston Lake properties, plus minority interests in Orano-Denisonco-owned McClean Lake and Midwest Joint Ventures

Strong balance sheet with ~CAD$430M of working capital, physical uranium and investments(2)

Denison's financial and liquid assets on hand, relative to flagship development project initial capex (~$CAD400M) is unrivaled and puts the company in an enviable position for project advancement

Focused on the infrastructure-rich Eastern Athabasca Basin in Saskatchewan, Canada Nuclear renaissance: 20+ nations pledge to triple nuclear energy capacity by 2050

NOTES: (1) See supporting slides for details. (2) As of December 31, 2023, for additional details see financial statements and MD&A for the period ended December 31, 2023.

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Diversified Athabasca Basin asset base with superior development leverage

PHOTO:

Aerial view of Denison's 22.5% owned McClean Lake mill facility

NOTES:

95%(1)

effective interest in

Flagship

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(3)

22.5%

interest in

Strategic McClean Lake Uranium Mill & Mines

11% of global uranium production

processed through mill

Mining restart approved using SABRE mining with planned 2025 production of ~800,000 lbs. U3O8 (4)

Excess licensed milling capacity

69.35%

interest in

Emerging

Waterbury Lake project

PEA stage development project(5)

Tthe Heldeth Túé ("THT") deposit highlights potential for future development project pipeline

Successful 2023 ISR field test(6)

(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

October 26, 2022.

(4) See news release dated

January 24, 2024.

(5) Refer to the Waterbury

Lake Technical Report

titled "Preliminary

Economic Assessment for

the Tthe Heldeth Túé

(J Zone) Deposit,

Waterbury Lake Property,

Northern Saskatchewan,

Canada" dated October

Participating interests in key development- 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(7)

~385,000

hectares of exploration ground(8)

30, 2020.

(6) See news release dated

November 6, 2023.

(7) See news release dated

August. 3, 2021.

(8) Denison direct land

position shown as of

December 31, 2023;

excludes the land

positions held by JCU.

4

Denison's development portfolio projects:

Positioned amongst the lowest all-in cost assets of UxC's First Tier

Sample of Global Production Costs - September 2023 (1)(2)(3)

$70.00

Planned and Producing Operations (with Mining Method)"Third/Fourth Tier" (up to ~US$92/lb U3O8)

NOTES:

8

"Second Tier"

O

$60.00

(up to ~US$48/lb U3O8

3

U

UxC's "First Tier"

USD$/lb

$40.00

$50.00

(includes lowest-cost projects with full costs up to ~US$33/lb U3O8)

-

US$25.47

Costs

$30.00

US$24.93

(2023)

US$16.04

(2020)

Full/in

$10.00

(2023)

$20.00

All-

$0.00

ISR

ISR

ISR

ISR

UG

ISR

UG

UG

UG UG UG

UG

ISR ISR

UG

OP

OP

ISR

OP

Denison/Canada		Canada		Kazakhstan		Australia		U.S.A.		Africa

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 September 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

Robust Balance Sheet with ~CAD$430M(1,2)

in working capital, physical uranium and investments

2.3M lbs U3O8

in holdings of

physical uranium at Dec. 31, 2023

Market value ~CAD$277M (US$91.00/lb U3O8)

+/- ~CAD$30M in change for every US$10/lb U3O8 move in spot price

Acquired at average cost of USD$29.66/lb U3O8

Long-term holding expected to enhance access to future project financing for flagship Wheeler River(2)

All material received and held in licenced North American storage facilities (Cameco + ConverDyn)

CAD$131M

in

cash and cash equivalents(1)

Working capital of CAD$135M(1)

CAD$26M

investments in

uranium equities and convertibles(3)

Significant equity and convertible debenture holdings in uranium exploration and development companies, including F3 Uranium Corp., Skyharbour Resources Ltd., & GoviEx Uranium Inc.

PHOTO:

Packaged U3O8 yellowcake at Denison's 22.5% owned McClean Lake mill.

NOTES:

(1) As of December 31,

2023, for additional

details see financial

statements and MD&A for

the period ended

December 31, 2023.

Working capital is a non-

IFRS financial measure

and is calculated as the

value of current assets

less the value of current

liabilities, excluding non-

cash current liabilities;

also excludes investment

in joint venture (JCU).

(2) See Denison's news

releases dated March 15,

2021, March 22, 2021, and

April 1, 2021.

(3) As of December 31,

Balance sheet position, relative to initial project capex for flagship development asset (Phoenix), is unrivaled among uranium development-stage peers

2023, for additional

details see financial

statements and MD&A for

the period ended

December 31, 2023;

includes investments in

uranium equities and

convertible debentures.

6

Environmental, Social, Governance & Indigenous (ESG+I)

Fundamental considerations driving Denison's operations

PHOTO:

Multiple

Indigenous

Agreements

In Place

• Shared Prosperity Agreement with English River First Nation(4)
• Participation/Funding and/or Exploration Agreements with: Kineepik Métis Local / Pinehouse(5), Ya'thi Néné Lands & Resources Office(6), and Métis Nation - Saskatchewan(7)

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 115 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(2, 4)

Authentic Social Programs

Denison's community / social

investment program targets community-based initiatives

Highlights of the Elders of Sakitawak's market garden in Ile a la Crosse,

1. community-basedinitiative sponsored by Denison.

LINKS:

Denison's ESG Report

ERFN SPA Signing Video

NOTES:

1. See news release dated December 2, 2021.
2. For more information:https://www.theglobeand mail.com/business/career s/management/board-games/article-the-globe-and-mails-comprehensive-ranking-of-canadas-corporate-boards-3/
3. See Denison's news release dated March 15, 2021.
4. See news release dated September 27, 2023.
5. See news release dated June 23, 2022.
6. See news release dated October 20, 2022.
7. See MD&A for the period ended Dec. 31, 2022
8. See Denison's Annual
   Information Form for additional details.

7

Large land position in the infrastructure-rich eastern portion of the Athabasca Basin(1)(2)

Waterbury Lake (Denison 69.35%)

McClean Lake Mill

Moon Lake South

(Denison 75%)

All Season Highway

/ Haul Road

Midwest

(Denison 25.17%)

Waterfound

(Denison 24.68%)(3)

McArthur River Mine

Wheeler River

(Denison 95%)(3)

Provincial Power Grid

(Denison 22.5%)

McClean Lake North

(Denison 22.5%)

Rabbit Lake Mill

NOTES:

(1) Denison direct land

Cigar Lake Mineposition shown as of December 31, 2023.

(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.

Key Lake Mill	8

95% 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 (U3O8)

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 U3O8

combined

Proven & Probable Reserves

(100% basis)

CAD$419M

Estimated (100% basis)

Initial CAPEX (Phoenix)

2023 Costing

in NI 43-101

Phoenix Feasibility Study and Gryphon PFS Update reflect current post-inflation costing environment

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

in the traditional territory of English River First Nation, in the	11,720
Located within the boundaries of Treaty 10
homeland of the Métis, and within Nuhenéné	hectares of prospective
	ground over 19 claims

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

Phoenix In-Situ Recovery ("ISR") Feasibility Study (2023):

Reflects rigour of multi-year technical de-risking and delivers impressive economic results(1)

PHOTOS:

70.5M

lbs U3O8

@

11.4%

U3O8

Measured &

Indicated

Mineral

Resources

(280,200 tonnes,

100% basis)

One of the highest- grade undeveloped uranium deposits globally

Including…

56.3M

lbs U3O8

@ 46.0% U3O8

M&I mineral resources for Zone A high-gradedomain

C$1.56B	C$419M
estimated	estimated
Base-case	Initial
post-tax NPV8%	CAPEX
(100% basis)	(100% basis)
(see note 2, 3)

90.0%	3.7 to 1
estimated	impressive
Base-case	Base-case
post-tax	post-tax NPV
IRR	to initial capital
(see note 2, 3)	cost ratio
US$6.28	US$16.04
/ lbs U3O8	/ lbs U3O8
average	average
Cash Operating	All-in
Costs	Cost(4)
(C$8.51/lb U3O8)	(C$21.73/lb U3O8)

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, Can ada" 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. Post-taxNPV, 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.
4. All-incost 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 U3O8 to be produced.

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