Osisko Mining : 2023 – Q2 – Management’s Discussion and Analysis

OSISKO MINING INC.

MANAGEMENT'S DISCUSSION AND ANALYSIS

FOR THE THREE AND SIX-MONTH PERIODS ENDED JUNE 30, 2023 AND 2022

This management's discussion and analysis (this "MD&A") reflects the assessment by management of the results and financial condition of Osisko Mining Inc. ("Osisko" or the "Corporation") and should be read in conjunction with the Corporation's unaudited interim financial statements for the three and six-month periods ended June 30, 2023 and 2022 and the notes thereto (the "Financial Statements"). Management is responsible for the preparation of the Financial Statements and this MD&A. The Financial Statements have been prepared in accordance with International Financial Reporting Standards ("IFRS") as issued by the International Accounting Standards Board (the "IASB"), applicable to the preparation of interim financial statements in accordance with IAS 34, Interim Financial Reporting. This MD&A and the Financial Statements are available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile and on Osisko's website (www.osiskomining.com), and should be read in conjunction with the audited consolidated financial statements of the Corporation for the years ended December 31, 2022 and 2021.

This MD&A has been prepared as of August 10, 2023. All dollar figures in this MD&A are expressed in Canadian dollars unless stated otherwise.

DESCRIPTION OF BUSINESS

The Corporation was incorporated on February 26, 2010 and exists under the Business Corporations Act (Ontario). The Corporation's focus is the exploration and development of gold resource properties in Canada. Currently, the Corporation is exploring in Québec and looking for new opportunities to enhance shareholder value.

Exploration Strategy

Osisko's flagship project is the high-gradeworld-class Windfall Gold Deposit (the "Windfall Project") located between Val-d'Or and Chibougamau in Québec, Canada, in which Osisko beneficially owns a 50% interest and is being developed in partnership with Gold Fields (as defined herein). The Windfall Project is currently one of the highest-grade undeveloped gold projects in the world. Osisko also holds a 50% interest in partnership with Gold Fields in a large area of claims totaling 223,109 hectares, mostly located in the Urban-Barry area and in the Quévillon area and includes the Osborne-Bell Gold Deposit.

The Corporation's strategy in partnership with Gold Fields is to advance and develop the Windfall Project towards a production decision while continuing to explore for additional deposits in the emerging districts of Urban Barry and Quévillon. In line with its strategy, the Corporation completed and filed the Windfall Feasibility Study (as defined herein) on January 10, 2023 and completed an Environmental Impact Assessment for the Windfall Project (the "Windfall EIA") on March 29, 2023. The Corporation also signed a definitive agreement with Miyuukaa Corp. ("Miyuukaa"), a wholly-owned corporation of the Cree First Nation of Waswanipi ("CFNW"), for the construction of a proposed transmission line facilities and the transportation of hydroelectric power to the Windfall Project. The Partnership (as defined herein) is advancing the Windfall Project towards the permitting process while advancing detailed engineering, Impact Benefit Agreement discussions, and procurement. Meanwhile, additional work such as conversion drilling, the underground works towards a fourth bulk sample in the Lynx 4 Zone, and regional exploration programs will continue to support the development plans for the Corporation. Drilling activities continue at the Windfall Project, mostly from underground with infill drilling in Lynx, Triple Lynx, and Lynx 4 Zones while continuing the expansion of the deposit footprint through new discoveries.

UPDATES DURING THE THREE AND SIX-MONTH PERIOD AND SUBSEQUENT TO THE PERIOD

Corporate Development and Acquisitions:

On July 17, 2023, Québec's Ministry of Natural Resources and Forests lifted the access restriction to forests and roads on Crown land in the Eeyou Istchee James Bay area surrounding the Windfall site. To help and support provincial fire-fighting efforts, Windfall camp lodged over 100 firefighters from the Québec fire-fighting agency, Société de Protection des Forêts Contre le Feu, who were using the Corporation's facilities as a base to fight regional fires. The Corporation resumed underground drilling activities later in the week, and increased all other regular site activities back to normal levels as the local fire situation continued to improve.

The Corporation published its 2022 Sustainable Development Report on July 18, 2023, which provided a detailed overview of the environmental, social, and governance performance and economic contributions in the communities in which it operates. The report is available on Osisko's website (www.osiskomining.com).

On June 5, 2023, Osisko provided the following update on the ongoing forest fire situation affecting the communities in Abitibi and Eeyou Istchee James Bay, where the Windfall Project is located. On June 2 and 3, 2023, Québec's Ministry of Natural Resource and Forests announced prohibitions regarding forest access on Crown lands, and closed forestry roads for reasons of public safety, given the situation related to wildfires in the Abitibi and Eeyou Istchee James Bay regions. Osisko and Windfall

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Mining Group have withdrawn the staff and continue to monitor the facilities remotely and on the ground in accordance with local directives. The team is in constant communication with local and provincial authorities to coordinate all efforts in this difficult time. All personnel are safe, and the facilities are secure. While all activities at site are currently suspended, Osisko does not anticipate any material impact on its business.

On March 29, 2023, Osisko announced that it had submitted the Windfall EIA to the Environmental and Social Impact Review Committee (the "COMEX").

On March 16, 2023, Osisko announced that it had signed a definitive agreement with Miyuukaa with respect to the construction of proposed transmission facilities and the transport of hydroelectric power to the Windfall Project. The power line from the Waswanipi substation to the Windfall Project is located entirely on CFNW traditional lands covered by the James Bay and Northern Québec Agreement.

Financings:

On February 28, 2023, Osisko completed a "bought deal" brokered private placement financing of 32,260,000 units of the Corporation at a price of $3.10 per unit for aggregate gross proceeds of approximately $100 million. Each unit consists of one common share in the capital of the Corporation (each, a "Common Share") and one-half of one Common Share purchase warrant of the Corporation (each whole warrant, a "Warrant"). Each Warrant entitles the holder thereof to acquire one Common Share until August 28, 2024 at a price of $4.00 per Common Share, subject to customary anti-dilution adjustments.

On February 2, 2023, Osisko completed a "bought deal" non-brokered private placement of an aggregate of 4,568,051 "flow- through" shares of the Corporation for aggregate gross proceeds of approximately $27.4 million.

Joint Venture on the Windfall Project:

On May 2, 2023, Osisko announced that it concluded a 50/50 joint venture with an affiliate of Gold Fields Limited ("Gold Fields") for the joint ownership and development of the Windfall Project (the "Transaction").

Transaction Highlights

The Transaction closed on May 2, 2023, with Gold Fields acquiring a 50% partnership interest in a partnership formed under the laws of the Province of Ontario, to be re-named "Windfall Mining Group" (the "Partnership"), which will develop the Windfall Project and the surrounding Urban Barry and Quévillon exploration properties (collectively, the "Property"). The Transaction was implemented in accordance with, among other things, a framework agreement dated May 2, 2023 (the "Framework Agreement") among Osisko, Gold Fields, Gold Fields Holdings Company Limited, the Partnership and 1000516419 Ontario Inc., the manager of the Partnership (the "Manager"). Pursuant to the terms of the Framework Agreement, Gold Fields acquired 50% interest in the Partnership for an aggregate consideration of $600 million in cash to Osisko. The partnership agreement governing the Partnership also required Gold Fields to sole fund up to $75 million in contributions to the Partnership (half of which is on behalf of Osisko) for regional exploration in accordance with the terms described below. Prior to the acquisition of the 50% Partnership interest by Gold Fields, Osisko had contributed to the Partnership the Property together with any claims, permits, leases, all other real property, personal property, contractual rights and other assets currently held or acquired for the benefit of the Property.

Key highlights of the Transaction include:

• Gold Fields made an initial cash payment to Osisko of $300 million.
• Gold Fields will make an additional cash payment to Osisko of $300 million on issuance of the applicable permits authorizing the construction, operation and mining of the Windfall Project (the "Deferred Payment Amount").
• Gold Fields will be required to sole fund expenditures for regional exploration up to a maximum of $75 million, after which regional exploration programs would be proportionately funded by each of Osisko and Gold Fields.
• Gold Fields is required to make two separate cash payments to Osisko totaling $34 million (the "Pre-Closing Paid Amounts").

1. 50% of the Pre-Closing Paid Amounts ($17 million) which has been paid to Osisko on July 31, 2023 and the remaining 50% will be payable on December 31, 2023.

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• 1. Pre-ClosingPaid Amounts represent Gold Field's share of the expenditures incurred by Osisko to advance the Windfall project from January 1, 2023.
• Gold Fields and Osisko will share all other project interim and construction costs on a 50/50 basis going forward.
• No cash taxes paid on proceeds to Osisko due to utilization of existing tax pools.
• Governance arrangements with equal representation in the Partnership from Osisko and Gold Fields, to leverage each party's skillsets.

Exploration Highlights:

Drilling Highlights

During the six-month period ended June 30, 2023, and subsequent to the period-end, Osisko provided several results from the ongoing drilling program. Drill highlights include the following*:

• 286 g/t Au over 2.1 metres and 204 g/t Au over 2.0 metres at Triple Lynx on April 5, 2023

• True width determinations are estimated at 55-80% of the reported core length intervals for most of the zones. The full set of drill results is available electronically on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile and Osisko's website (www.osiskomining.com).

Regional Exploration Program

In early 2023, Osisko commenced a new regional exploration program on the Urban-Barry gold project located in the Abitibi greenstone belt, Eeyou Istchee James Bay, Québec (the "Urban-Barry Project"), in which Osisko holds a 50% interest through the Partnership.

The regional exploration program is designed to explore areas outside the main Windfall gold deposit in the Urban-Barry volcanic belt with 30,000 metres of drilling. Near deposit exploration targets include a high-potential exploration area identified in the hanging wall of the Bank Fault, 1.5 kilometres east-northeast of the Lynx Zone of the Windfall Project. Additional work on previously identified showings (including Golden Bear and Fox) and on new showings and targeted structures parallel to the main Windfall gold deposit are also to be included in the program.

The winter drilling program ended on May 13, 2023. The regional exploration activities are expected to resume at the beginning of August with a drilling program of approximately 12,000 metres on the Quévillon Osborne-Bell Project and areas outside the main Windfall gold deposit in the Urban-Barry volcanic belt.

Windfall Feasibility Study

On January 10, 2023, Osisko filed the Windfall Feasibility Study, which is available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile. All figures in this section are on a 100%-project basis.

Windfall Feasibility Study Highlights*

• Full-yearaverage production of 306,000 oz Au, 8.1 g/t Au average grade fully diluted
• Peak production of 374,000 oz Au in year two
• Average after-tax free cash flow of C$257 million per full year of production (C$2.3 billion cumulative free cash flow)
• Capex of US$607 million (includes US$38 million as contingency in direct and indirect costs), NPV/Capex ratio of 1.5
• All-insustaining cost ("AISC") of US$758/oz; cash cost of US$587/oz
• 3,400 tonne per day milling operation
• Average recovery of 93%; all-in mining cost of US$136/tonne

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• C$6.2 billion of gross revenue
• Creation of over 1,000 direct and indirect jobs during construction and over 670 direct permanent jobs during operation

• Cautionary Statement: The reader is advised that the results of the Windfall Feasibility Study summarized in this MD&A are intended to provide only an initial, high-level overview of the Windfall Project potential and design options. The highlights are supported by the Windfall Feasibility Study.

Notes:

1. The Windfall Feasibility Study mine plan and economic model include numerous assumptions. There is no guarantee the project economics described herein will be achieved.
2. Full years of production refer to Years 1 to 9.
3. AISC is presented within the meaning defined by the World Gold Council ("WGC"), less corporate G&A.
4. Total cash costs and cash costs per ounce, and AISC and AISC per ounce are non-IFRS financial measures. See "Non-IFRSFinancial Measures" for a discussion of non-IFRS financial measures.
5. References to C$ and US$ are to Canadian and United States dollars, respectively.

The Windfall Feasibility Study Details

The Windfall Feasibility Study was integrated by BBA Inc. under the supervision of Ms. Kim-Quyên Nguyên, P. Eng., MBA, Project Director of Osisko, and Osisko's technical team. This independent feasibility study was prepared in collaboration with the following firms: A2GC − Andrieux & Associates Geomechanics Consulting L.P. (Montréal, QC), BBA Inc. (Montréal, QC), GCM Consultants (Montréal, QC), Entech Mining Ltd. (Toronto, ON), PLR Resources Inc. (Montréal, QC) and WSP Canada Inc. (Montréal, QC). These firms provided mineral resource estimates, reserve estimates, design parameters, and cost estimates for mine operations, process facilities, major equipment selection, waste and tailings storage, reclamation, permitting, and operating and capital expenditures. Contributors and their areas of responsibility are summarized in the Windfall Feasibility Study. Project economics were evaluated based on a forecast date to receive the construction permit in Q1 2024. Unless stated otherwise, all costs are in Canadian dollars. All figures in this section are on a 100%-project basis.

Table 1: FS Summary at US$1,600/oz Au

Total mineralized material mined (t)	12,183,405
Average mill feed diluted gold grade (Au g/t)	8.06
Total gold contained (oz)	3,158,713
Total gold produced (oz)	2,942 339
Total gold payable (oz)	2,940,868
Gold payable recovery (%)	93.1%
Average annual gold produced (Au oz per year)	294,234
Average mill feed diluted silver grade (Ag g/t)	4.18
Silver payable recovery (%)	83.3%
Total silver payable (oz)	1,366,537
Total initial CAPEX (C$million)	788.6
Sustaining capital (C$Million)	587.6
Operating cost (per tonne milled)
Mining (C$)	82.21
Processing (C$)	40.76
Waste & water management (C$)	6.30
General & administration (C$)	32.81
Electrical transmission line lease (C$)	14.59
Total unit operating costs (per tonne milled) (C$)	176.67

Table 2: Summary Economics at US$1,600 Au

LOM net smelter return ("NSR") revenue (C$Million) Total LOM pre-tax cash flow (C$Million)

Average annual pre-tax cash flow (C$Million)

6,134

2,432

243

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