Osisko Mining : 2024 – Q1 – Management’s Discussion and Analysis

OSISKO MINING INC.

MANAGEMENT'S DISCUSSION AND ANALYSIS

FOR THE THREE-MONTH PERIODS ENDED MARCH 31, 2024 AND 2023

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-month periods ended March 31, 2024 and 2023 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, 2023 and 2022.

This MD&A has been prepared as of May 1, 2024. 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 by Windfall Mining Group (the "Partnership"), a partnership formed between Osisko and Gold Fields Limited ("Gold Fields") with each of Osisko and Gold Fields holding a 50% interest in the Partnership. The Windfall Project is currently one of the highest-grade undeveloped gold projects in the world and is the highest-grade undeveloped gold project to be discovered in Québec. The Partnership holds a large area of claims totaling 223,379 hectares, mostly located in the Urban-Barry area and the Quévillon area.

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, Québec. In line with this strategy, Osisko 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. Power hook-up to Windfall as completed on January 18, 2024. The Partnership is advancing the Windfall Project towards mine permitting while advancing detailed engineering, Impact Benefit Agreement discussions, and procurement. Meanwhile, additional work such as conversion drilling, underground advancement towards a fourth bulk sample in the Lynx 4 Zone, and regional exploration programs continue to support the development plans for the Corporation. Drilling activities are ongoing at the Windfall Project, with infill drilling primarily in the Lynx Zones, and continuing the expansion of the deposit footprint through exploration holes.

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 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, named "Windfall Mining Group". The Partnership has been formed to develop the Windfall Project and the surrounding Urban Barry and Quévillon, Québec 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. 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

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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 has agreed to 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.
• 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 was 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) was paid to Osisko on July 31, 2023, and the remaining 50% was paid on December 31, 2023.

• 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 the skills, relationships, and expertise of each party.

UPDATES DURING THE PERIOD AND SUBSEQUENT TO THE PERIOD

Corporate Development and Acquisitions:

On January 18, 2024, Osisko announced grid power at the Windfall Project. The 85 km long 69 kV hydro-electric power line built, owned and operated by the CFNW was completed on schedule, and grid power had successfully been connected to the Windfall Project. The use of hydroelectricity at the Windfall Project marks the switching over from diesel generated electricity to operate the camp and underground infrastructure, which the Corporation anticipates will significantly reduce both power costs and greenhouse gas emissions at the site.

Exploration Highlights:

Drilling Highlights

During the three-month period ended March 31, 2024, and subsequent to the period-end, Osisko, through the Partnership, drilled a total of 41,807 metres at the Windfall Project including 25,867 metres from underground.

Regional Exploration Program

In 2024, the Partnership engaged in a regional exploration program outside the footprint of the Windfall deposit and on the Urban-Barry volcanic belt located in the Abitibi greenstone belt, Eeyou Istchee James Bay, Québec. The program was designed to explore gold bearing structures, including a high potential area located 5km northeast of the Lynx zone along the Bank Fault. Moreover, near deposit exploration targets also include an area located 4 km west of the Windfall deposit with a very similar geological setting to the Lynx portion of the Windfall deposit. Pursuant to this regional exploration program, 22,774 metres in drilling have been completed during the three-month period ended March 31, 2024.

During the first quarter of 2024, Osisko began a 35,000-metre drill program on certain Urban-Barry properties held by Bonterra Resources Inc. (TSXV:BTR) ("Bonterra") (hosting the Gladiator and Barry deposits) and adjoining Duke and Lac Barry

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properties (collectively, the "Phoenix Properties") as part of its 70% earn-in option with Bonterra. The program will initially focus on the Moss showing, located 5 kilometres south-west along strike from the Windfall Project.

Overall Performance:

During the three-month period ended March 31, 2024, the Corporation had approximately $4.1 million of exploration and evaluation expenditures. In the same period, the Partnership had approximately $38.1 million of exploration and evaluation additions, and $168.8 million of property, plant and equipment additions. In the same period the Corporation incurred $2.6 million on general and administration expenses (including salaries and benefits).

During the three-month period ended March 31, 2024, Osisko completed 17,221 metres of drilling on the Phoenix Properties. During the three-month period ended March 31, 2024, the Partnership completed an additional: (i) 41,807 metres of drilling on the Windfall Project; and (ii) and 6,864 metres of drilling on the Urban-Barry Project, for a combined total drilling campaign of 134,023 metres during the period beginning May 2, 2023 and ending on March 31, 2024. Management believes these fundamental elements provide a robust base necessary to build a mining company that could generate value for its shareholders over time. See the tables in Section 2 - "Mineral Resources and Mineral Reserves" of this MD&A for the grade and quantity of each category of mineral resources and mineral reserves included in the foregoing disclosure.

Several other milestones have been reached at the Windfall Project during the three-month period ended March 31, 2024, including grid power at the Windfall Project. The 85 km long 69 kV hydro-electric power line built, owned and operated by the CFNW was completed on schedule, and grid power had successfully been connected to the Windfall Project. As well as the completion of the underground pumping station, commencement of the underground garage and approximately 43% completion of the water treatment plant. During the three-month period ended March 31, 2024, the exploration ramp was advancing toward the 4th bulk sample zone in Triple Lynx, and 664 metres were advanced with a total advancement of the exploration ramp at 13,143 metres.

As of March 31, 2024, the Lynx underground exploration ramp was at a vertical depth of approximately 640 metres below surface. Osisko and the Partnership continue to advance underground infrastructure at the Windfall Project. A series of ventilation raises and secondary egress from surface down to the 580-metre level were completed. In addition, installation of long-term evolution infrastructure has commenced underground, and construction of a new pumping station was completed on the 460-metre level.

1. SUMMARY OF MINERAL PROPERTIES

The Corporation's gold mineral properties in Canada are summarized below:

Continuing Exploration Properties	Location	Status
Windfall	Québec	Owned 50%(1)
Quévillon Osborne-Bell	Québec	Owned 50%(1)
Urban-Barry	Québec	Owned 50%(1)
Blondeau-Guillet	Québec	Owned 100%(2)
Phoenix	Québec	Earn-in 70%(4)
Urban Duke	Québec	Owned 30%(3)

Notes:

1. Represented by a 50% interest in the Partnership. Prior to the completion of the Transaction on May 2, 2023, this property was 100% owned by Osisko.
2. Vior Inc. ("Vior") has entered into an earn-in right to acquire up to 75% interest on the property on August 24, 2021.
3. Bonterra has an earn-in right of 70% on the property which was executed on July 12, 2021 (subject to the below).
4. Osisko has an earn-in right for 70% of the Phoenix Properties (which, for the avoidance of doubt, includes Urban Duke).

2. MINERAL RESOURCES AND MINERAL RESERVES

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.

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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
• 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. Reference should be made to the full text of the Windfall Feasibility Study for the assumptions, qualifications and limitations therein, a copy of which is available on SEDAR+ (www.sedarplus.com) under Osisko's issuer profile.

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.

Windfall Mineral Resource Estimate

On January 10, 2023, Osisko filed the Windfall Feasibility Study. The Windfall mineral resource estimate, which has an effective date of the June 7, 2022 (the "Windfall MRE") shown in Table 2, is included in the Windfall Feasibility Study. The Windfall MRE uses a base cut-off of 3.5 g/t Au in the measured mineral resource, indicated mineral resource and inferred mineral resource categories. The Windfall MRE is reported inclusive of the mineral reserve estimate. Mineral resources are not mineral reserves as they have not demonstrated economic viability. All figures in this section (including information in the tables below) are on a 100%-project basis.

Highlights:

• 4.1 M oz Au measured & indicated ("M&I") resource averaging 11.4 g/t Au.*
• M&I resource ounces increase of 26% (0.8 M oz Au).*
• M&I resource grade increase of 8%.*
• Lynx contains 65% of MRE total (M&I 3.1 M oz averaging 13.0 g/t Au; inferred 1.7 M oz averaging 10.8 g/t Au).*
• 50% of the Windfall MRE is hosted in 26 wireframes; 75% of the Windfall MRE is hosted in 97 wireframes.
• 98% of the Windfall MRE is located from surface to 1,200 metres vertical depth.
• • See Table 2 (entitled "The Windfall MRE by Area (3.5 g/t Au cut-off)") for a complete breakdown of the measured mineral resources and indicated mineral resources comprising the M&I figures presented herein.

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Table 1: Windfall MRE Sensitivity Table

	Cut-off				Measured + Indicated				Inferred
	Grade							Ounces			Grade			Ounces
	(g/t Au)		Tonnes	Gold		Grade	Gold	Ag	Tonnes	Gold	Ag		Gold	Ag
			(000 t)	(g/t)		Ag (g/t)	(000 oz)	(000 oz)	(000 t)	(g/t)	(g/t)		(000 oz)	(000 oz)
5.00		8,213	13.9		7.0	3,667	1,854	7,986	10.7	6.0		2,760	1,545
4.50		9,029	13.1		6.7	3,791	1,935	9,078	10.0	5.6		2,927	1,638
4.00		9,950	12.2		6.3	3,917	2,020	10,561	9.2	5.2		3,129	1,754
3.50		11,061	11.4		5.9	4,050	2,114	12,287	8.4	4.8		3,337	1,892
3.00		12,388	10.5		5.6	4,188	2,217	14,299	7.7	4.4		3,547	2,033
2.50		13,951	9.6		5.2	4,326	2,330	17,178	6.9	4.0		3,801	2,219

Notes:

1. Values are rounded to the nearest thousand which may cause apparent discrepancies.
2. The Windfall MRE cut-off: 3.5 g/t Au
3. The cut-off grade variation is not applicable to the material in the stockpile.

Table 2: The Windfall MRE by Area (3.5 g/t Au cut-off)

Measured

Indicated

Inferred

Area

Gold

Grade

Gold(1)

Ounces

Tonne(1)

Gold

Grade

Gold(1)

Ounces

Tonne(1)

Gold

Grade

Gold(1)

Ounces

Tonnes(1)

Ag

Ag(1)

Ag

Ag(1)

Ag

Ag(1)

(000 t)

(g/t)

(g/t)

(000 oz)

(000 oz)

(000 t)

(g/t)

(g/t)

(000 oz)

(000 oz)

(000 t)

(g/t)

(g/t)

(000 oz)

(000 oz)

Lynx(2)	671	11.4	7.2	247	154	6,638	13.2	6.7	2,814	1,426	4,774	10.8	6.9	1,663	1,063
Underdog	-	-	-	-	-	928	9.5	3.4	284	101	4,072	7.7	3.0	1,011	397
Main(3)	109	9.4	4.4	33	16	2,685	7.6	4.8	655	412	2,799	5.8	3.3	518	296
Triple 8	-	-	-	-	-	-	-	-	-	-	642	7.0	6.6	145	136
Total (in	780	11.1	6.8	279	170	10,250	11.4	5.9	3,754	1,939	12,287	8.4	4.8	3,337	1,892
situ)
Stockpile	32	16.9	4.3	17	4	-	-	-	-	-	-	-	-	-	-
s(4)
Total	811	11.4	6.7	297	174	10,250	11.4	5.9	3,754	1,939	12,287	8.4	4.8	3,337	1,892

Notes:

1. Values are rounded to the nearest thousand which may cause apparent discrepancies.
2. Lynx area includes Lynx Main, Lynx HW, Lynx SW, Lynx 4, and Triple Lynx.
3. Main area includes Zone 27, Caribou 1&2, Caribou Extension, Bobcat, Mallard, Windfall Nord, and F-Zones.
4. Cut-offgrade is not applicable to the stockpiles.

* See the Windfall MRE notes further below.

The Windfall MRE is based on the result of 4,834 drill holes (1,852,861 metres of core) in the resource area, including 4,152 drill holes (1,665,282 metres of core) completed by Osisko from October 2015 to May 2022, and assays up to June 7, 2022. Readers are encouraged to read the full text of the Windfall Feasibility Study, which includes the Windfall MRE and which has been prepared in accordance with National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("NI 43-101"), a copy of which is available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile.

The Windfall MRE reflects the current status of the geological interpretation supported by infill drilling, underground mapping, and bulk sample results. Most mineralized envelopes in the Main area are associated with pyritic stringers. Lynx and Underdog mineralized lenses predominantly form an extensive anastomosed network of quartz-rich and pyrite-rich veins. The mineralization system is located near contacts between volcanic and pre-mineral intrusive rocks in the Main and Lynx areas, and more specifically, within pre-mineral intrusive units in Underdog.

The Windfall MRE is 50% contained within 26 wireframes and 75% contained within 97 wireframes. The Windfall MRE considers a total of 579 mineralized lenses defined by individual wireframes with a minimum true thickness of 2.0 metres. The Windfall MRE reports grade blocks inside volumes potentially mineable by underground methods at a cut-off grade of 3.5 g/t Au.

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Table 3: Parameters used to estimate the underground cut-off grade for the Windfall MRE

Parameters	Unit	Value
Gold Price	USD/oz	1,600
Exchange Rate	USD/CAD	1.28
Mill Recovery	%	93.0
Payability	%	99.95
Sell Cost	USD/oz	5
NSR Royalties	%	2
Mining Cost	CAD/T milled	125
G&A Cost	CAD/T milled	39
Processing Cost	CAD/T milled	42
Environment	CAD/T milled	4
Calculated Cut-off Grade	g/t Au	3.51
MRE Cut-off Grade	g/t Au	3.5

Notes:

1. The independent qualified person for the Windfall MRE, within the meaning of NI 43-101, is Pierre-Luc Richard, P. Geo. (OGQ#1119), of PLR Resources Inc. The effective date of the Windfall MRE is June 7, 2022.
2. The Windfall MRE follows the November 29, 2019, CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines.
3. These mineral resources are not mineral reserves as they have not demonstrated economic viability. The quantity and grade of reported inferred mineral resources outlined in this MD&A are uncertain in nature and there has been insufficient exploration to define these resources as indicated or measured mineral resources; however, it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration. Resources are presented undiluted and in situ and are considered to have reasonable prospects for economic extraction. Isolated and discontinuous blocks above the stated cut-off grade are excluded from the mineral resource estimate. Must- take material, i.e., isolated blocks below cut-off grade located within a potentially mineable volume, was included in the mineral resource estimate.
4. Mineral resources are reported inclusive of those mineral resources converted to mineral reserves.
5. As of June 7, 2022, the database comprises a total of 4,834 drill holes for 1,852,861 metres of drilling in the area extent of the mineral resource estimate, of which 4,152 drill holes (1,665,282 metres) were completed and assayed by Osisko. The drill hole grid spacing is approximately 12.5 metres x 12.5 metres for definition drilling, 25 metres x 25 metres for infill drilling and larger for extension drilling.
6. All core assays reported by Osisko were obtained by analytical methods described below under "Quality Control and Reporting Protocols".
7. Geological interpretation of the deposit is based on lithologies, mineralization style, alteration, and structural features. Most mineralization envelopes are subvertical, striking NE-SW and plunging approximately 40 degrees towards the North-East. The 3D wireframing was generated in Leapfrog Geo, a modeling software, from hand selections of mineralization intervals. The Windfall MRE includes a total of 579 tabular, mostly sub- vertical domains defined by individual wireframes with a minimum true thickness of 2.0.
8. Assays were composited within the mineralization domains into 2.0 metres length composites. A value of 0.00125 g/t Au and 0.0025 g/t Ag (¼ of the detection limit) was applied to unassayed core intervals.
9. High-gradecomposites were capped. Capping was determined in each zone from statistical studies on groups of lenses sharing similar mineralization characteristics. Capping varies from 6 g/t Au to 200 g/t Au and from 5 g/t Ag to 150 g/t Ag. A three-pass capping strategy defined by capping values decreasing as interpolation search distances increase was used in the grade estimations.
10. Block models were produced using Datamine™ Studio RM Software. The models are defined by parent cell sizes of 5 metres EW, 2 metres NS and 5 metres height, and sub-blocked to minimum sub-cell sizes of 1.25 metres EW, 0.5 metres NS and 1.25 metres height.
11. Ordinary Kriging based interpolations were produced for gold estimations in each zone of the Windfall deposit, while silver grade estimations were produced using Inverse Distance Squared (ID2) interpolations. Gold estimation parameters are based on composite variography analyses. The gold estimation parameters were used for the silver estimation.
12. Density values between 2.74 and 2.93 were applied to the mineralized lenses.
13. The Windfall MRE is categorized as measured, indicated, and inferred mineral resource as follows:

The measured mineral resource category is manually defined and encloses areas where:

I. drill spacing is less than 12.5 metres;

II. blocks are informed by mostly four drill holes;

1. geological evidence is sufficient to confirm geological and grade continuity; IV. lenses have generally been accessed by underground workings.

The indicated mineral resource category is manually defined and encloses areas where:

I. drill spacing is generally less than 25 metres;

II. blocks are informed by mostly three drill holes;

1. geological evidence is sufficient to assume geological and grade continuity. The inferred mineral resource category is manually defined and encloses areas where:
   I. drill spacing is less than 100 metres;

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II. blocks are informed by a minimum of two drill holes;

1. 1. geological evidence is sufficient to imply, but not verify geological and grade continuity.
2. Tonnage and gold grade of the stockpiles were estimated using the grade control model. Densities by lithologies, ranging from 2.76 to 2.84, were used in the estimation of the tonnages. Gold grades were estimated with an average of muck samples results for every round tonnage, based on muck samples with an average sample weight of 3.4 kilograms taken every 8-yard scoop bucket. The sampling capping varying between 60 g/t Au to 80 g/t Au was applied on the muck gold grade results. An average per silver grade estimates in the stockpiles was reported from the resource block model as silver was not analyzed in the muck samples.
3. The mineral resource is reported at 3.5 g/t Au cut-off. The cut-off grade is based on the following economic parameters: gold price at 1,600 USD/oz, exchange rate at 1.28 USD/CAD, 93% mill recovery; payability of 99.95%; selling cost at 5 USD/oz, 2% NSR royalties, mining cost at 125 CAD/t milled, G&A cost at 39 CAD/t milled, processing cost at 42 CAD/t, and environment cost at 4 CAD/t.
4. Estimates use metric units (metres (m), tonnes (t), and g/t). Metal contents are presented in troy ounces (metric tonne x grade / 31.103475).
5. The independent qualified person is not aware of any known environmental, permitting, legal, title-related, taxation, socio-political or marketing issues, or any other relevant issue that could materially affect the Windfall MRE.

Windfall Mineral Reserve Estimate

The Windfall mineral reserve estimate (the "Windfall Mineral Reserve") includes measured mineral resources and indicated mineral resources but does not include any inferred mineral resources. The total probable mineral reserves at Windfall are estimated at 12.2 million tonnes at 8.06 g/t Au for 3.16 million ounces of gold and 4.18 g/t Ag for 1.64 million ounces of silver.

Table 4: Mineral Reserves Estimate of the Windfall Project

										Probable
	Area			Tonnes			Grade			Grade			Ounces Au			Ounces Ag
			(000 t)			Au (g/t)			Ag (g/t)			(000 oz)			(000 oz)
	Lynx(1)	8,882		8.83		4.58			2,523		1,307
	Underdog	906		6.80		2.31			198		67
	Main(2)	2,363		5.55		3.44			422		261
	Total in situ	12,151		8.04		4.19			3,143		1,635
	Stockpiles	33		15.24		3.74			16		4
	Total	12,183		8.06		4.18			3,159		1,639

1. Lynx area includes: Lynx Main, Lynx HW, Lynx SW, Lynx 4, and Triple Lynx.
2. Main area includes: Zone 27, Caribou 1, Caribou 2, Caribou Extension, Bobcat, Mallard, Windfall North, and F-Zones.

Notes:

1. The independent qualified person for the Windfall Mineral Reserve, within the meaning of NI 43-101, is Patrick Langlais, P. Eng. (OIQ#6021556), of Entech Mining Ltd. The effective date of the estimate is November 25, 2022.
2. The Windfall Mineral Reserve follows the May 19, 2014 "CIM Definition Standards for Mineral Resources and Mineral Reserves" and the November 29, 2019 "CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines".
3. These mineral reserves have been diluted based on geotechnical recommendations and have had a mining recovery applied.
4. Values are rounded to the nearest thousand, which may result in apparent discrepancies.
5. The mineral reserve is depleted for all mining to November 3, 2022.
6. The mineral reserve is reported using a 3.5-g/tbreak-even, a 2.5-g/t stope incremental, and a 1.7-g/t marginal cut-off grade.
7. All measured mineral resources have been classified as probable mineral reserves.
8. Stockpile values were provided by Osisko and account for less than 1% of mineral reserve ounces.
9. Estimates use metric units (metres (m), tonnes (t), and g/t). Metal contents are presented in troy ounces (metric tonne x grade / 31.103475).
10. The independent qualified person is not aware of any known environmental, permitting, legal, title-related, taxation, socio-political or marketing issues, or any other relevant issue that could materially affect the Windfall Mineral Reserve.

All figures in this section are on a 100%-project basis.

Osborne-Bell Mineral Resource Estimate

Cut-off grade	Tonnes (T)(9)	Grade (g/t)	Ounces Au(12)
> 6.00 g/t Au	883,000	9.77	277,000
> 5.00 g/t Au	1,273,000	8.44	346,000
> 4.00 g/t Au	1,816,000	7.26	424,000
> 3.50 g/t Au	2,156,000	6.70	465,000
> 3.00 g/t Au	2,587,000	6.13	510,000
> 2.50 g/t Au	3,166,000	5.51	560,000

Notes:

1. Resources are presented undiluted and in situ and are considered to have reasonable prospects for economic extraction.
2. The estimate encompasses nine tabular gold-bearing zones each defined by individual wireframes with a minimum true thickness of 2 metres.

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1. High-gradecapping was done on composite data and established on a per-zone basis for gold. It varies from 25 g/t Au to 55 g/t Au.
2. Density values were applied on the following lithological basis (g/cm3): volcanic host rocks = 2.80; late barren dykes and Beehler stock = 2.78; Zebra felsic unit = 2.72.
3. Grade model resource estimation was evaluated from drill hole data using an Ordinary Kriging interpolation method on a block model using a block size of 2.5 metres x 2.5 metres x 2.5 metres.
4. The mineral resources presented herein are categorized as inferred mineral resources. The inferred mineral resources category is only defined within the areas where drill spacing is less than 100 metres and shows reasonable geological and grade continuity.
5. The resource was estimated using Geovia GEMS 6.8. The estimate is based on 931 surface diamond drill holes. A minimum true thickness of 2.0 metres was applied, using the grade of the adjacent material when assayed, or a value of zero when not assayed.
6. Estimates use metric units (metres, tonnes, and g/t). Metal contents are presented in troy ounces (metric tonne x grade / 31.10348).
7. The number of metric tonnes was rounded to the nearest thousand. Any discrepancies in the totals are due to rounding errors.
8. InnovExplo Inc. is not aware of any known environmental, permitting, legal, title-related, taxation, socio-political, or marketing issues, or any other relevant issue not reported in the Quévillon Resource Estimate (as defined herein) that could materially affect the mineral resource estimate.
9. These mineral resources are not mineral reserves as they do not have demonstrated economic viability. The quantity and grade of reported inferred resources in the Quévillon Resource Estimate are uncertain in nature and there has been insufficient exploration to define these inferred resources as indicated or measured, and it is uncertain if further exploration will result in upgrading them to these categories.
10. The number of ounces was rounded to the nearest thousand. Any discrepancies in the totals are due to rounding errors.

The Partnership's global mineral resources are summarized below:

CATEGORY	TONNES (MT)	AU GRADE (G/T)	AU (M OZ)
	TOTAL MEASURED
WINDFALL(1)	0.8	11.4	0.3
	TOTAL INDICATED
WINDFALL(1)	10.3	11.4	3.8
	TOTAL MEASURED & INDICATED
WINDFALL(1)	11.1	11.4	4.1
	TOTAL INFERRED
WINDFALL(1)(2)	12.3	8.4	3.3
OSBORNE-BELL(2)(3)	2.6	6.1	0.5
	14.9	8.0	3.8

Notes:

1. Information relating to the mineral resource estimate at Windfall is supported by the Windfall Feasibility Study.
2. Inferred mineral resources have a great amount of uncertainty as to their existence and as to whether they can be mined legally or economically. It cannot be assumed that all or any part of the inferred mineral resources will ever be upgraded to a higher category. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
3. Information relating to the Osborne-Bell Gold Deposit is supported by the Quévillon Resource Estimate. A cut-off grade of 3.0 g/t Au was used.

3. MINERAL PROPERTY ACTIVITIES

As of March 31, 2024, the Corporation held a significant claims position in the Urban-Barry and Quévillon area of Québec. Osisko's properties, held within the Partnership, cover more than 226,969 hectares and, as of the date of this MD&A, the Windfall Project is the Partnership's only material property.

The Corporation's properties include:

1. Windfall Project

The Windfall Project is 100% owned by the Partnership, in which Osisko holds a 50% partnership interest, and is located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec, Canada. The Windfall Project contains 325 claims covering 14,299 hectares. The Windfall Project is subject to NSR royalties varying from 1.0% to 3.0%. However, the majority of the claims comprising the mineral reserve estimate described in the Windfall Feasibility Study, are subject to a 2.0% NSR royalty held by Osisko Gold Royalties Ltd ("Osisko GR"). Further details of the royalties applicable to the Windfall Project are described in the Windfall Feasibility Study. The Windfall EIA was submitted to the COMEX on March 29, 2023.

Exploration Activities

During the three-month period ended March 31, 2024, an aggregate of 41,807 metres had been drilled at the Windfall Project including 25,867 metres of underground drilling. As a result, Osisko has completed an aggregate of 1,869,441 metres of drilling on the Windfall Project up to May 2, 2023 and the Partnership has drilled approximately 119,489 metres.

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The Windfall Project remains open down plunge, towards the east and at depth, as well as towards the north portion of the syncline fold encompassing most of the Lynx mineralized system.

The current underground drilling program is designed to convert the existing mineralized zones within the main deposit area and the Lynx zones into measured and indicated resource categories. Osisko continues to work in the exploration ramp within the mineralized zones of Triple Lynx and continues to develop underground drilling stations in order to accelerate the infill drilling process.

Additional information regarding drilling results, maps, and tables is available on SEDAR+ (www.sedarplus.ca) under Osisko's issuer profile and on Osisko's corporate website (www.osiskomining.com).

1. Urban-BarryProperty

The Urban-Barry Project is 100% owned by the Partnership, in which Osisko holds a 50% partnership interest. The Urban- Barry Project comprises 1,296 claims covering 70,596 hectares and is adjacent to the Windfall Project. The property is mostly constituted by claims that were acquired through designation in different years from 2015 to 2017 as well as the claims from the Corporation's acquisition of Beaufield Resources Inc. ("Beaufield"). The claims are subject to NSR royalties, further details of which are described in the Windfall MRE.

Exploration Activity

During the three-month period ended March 31, 2024, an aggregate of 6,864 metres had been drilled at the Urban-Barry Project by the Partnership. As a result, Osisko has completed an aggregate of 105,147 metres of drilling on the Urban Barry Project up to May 2, 2023 and the Partnership has drilled 8,642 metres.

1. Quévillon Osborne-Bell Project

The Quévillon Osborne-Bell Project is 100% owned by the Partnership, in which Osisko holds a 50% partnership interest, and is located 17 kilometres northwest of the town of Lebel-sur-Quévillon and 112 kilometres west of the Windfall Project. The Quévillon Osborne-Bell property, which includes the Osborne-Bell Gold Deposit, contains 2,581 claims covering more than 138,484 hectares.

The Osborne-Bell Gold Deposit has been the object of significant historical drilling over the past 30 years. The project was initially acquired on April 27, 2017, through the acquisition of a property package in the Lebel-sur-Quévillon area of Québec for cash consideration of $1 million and the issuance of 100,000 common shares of the Corporation ("Common Shares"). Expansion of the property was completed mostly through claims staking acquisition but also through different purchase agreements from individuals or companies since 2017. While there is no existing royalty covering the Osborne-Bell Gold Deposit, a few claims are subject to different NSR royalties varying from 1-3.5%, further details of which are described in the Quévillon Resource Estimate.

The land position of the Quévillon area covers volcano-sedimentary Archean greenstones that host several known gold showings and porphyry igneous intrusions that are of strong exploration interest to the Corporation.

Exploration Activity

During the three-month period ended March 31, 2024, no metres were drilled on the property.

1. Blondeau-GuilletProperty

The Blondeau-Guillet property consists of 74 claims covering 3,522 hectares.

On August 24, 2021, Vior acquired the right to purchase a 51% undivided interest in the Blondeau-Guillet property ("First Option") by issuing common shares of Vior to Osisko for a value totaling $225,000 in accordance with the following schedule:

1. $75,000 on or before the first anniversary of the option agreement, which shall be a firm commitment by Vior; (ii) $75,000 on or before the second anniversary of the option agreement; and (iii) $75,000 on or before the third anniversary of the option agreement and by incurring work commitments totaling at least $1,250,000 as follows: (i) a minimum of $250,000 on or before the first anniversary of the option agreement; and (ii) a further $1,000,000 on or before the third anniversary of the option agreement. Subject to the prior exercise of the First Option, Vior shall have the right to acquire an additional 24% undivided interest in the property by incurring additional work commitments totaling at least $1,750,000 over a three-year period. Upon satisfaction of the option agreement, Osisko and Vior will form an industry-standard joint venture on the property with Vior

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