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OSISKO DEVELOPMENT ANNOUNCES POSITIVE FEASIBILITY STUDY RESULTS FOR THE CARIBOO GOLD PROJECT 163,695 Ounces of Average Annual Gold Production Over 12 Year Mine Life Bulk Tonnage UG Mining with Ore Sorting to Minimize Cost & Environmental Footprint

Economic Studies Metallurgy & Processing

NYSE: ODV TSXV: ODV NEWS RELEASE

OSISKO DEVELOPMENT ANNOUNCES POSITIVE FEASIBILITY STUDY RESULTS

FOR THE CARIBOO GOLD PROJECT

163,695 Ounces of Average Annual Gold Production Over 12 Year Mine Life

Bulk Tonnage UG Mining with Ore Sorting to Minimize Cost & Environmental Footprint

Initial Probable Mineral Reserves of 2.03 Moz of Gold (16.7 Mt at 3.78 g/t Au)

After-tax NPV5% of C$502 Million and 20.7% IRR (unlevered) at US$1,700/oz Au

EA Certificate Process Progressed to Final Effects Assessment Phase

(All dollar amounts are expressed in Canadian dollars, unless otherwise indicated)

Montreal, Québec, January 3, 2023 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") is pleased to announce the results of an independent Feasibility Study

("FS" or the "Technical Report") prepared by BBA Engineering Ltd. ("BBA") in accordance with National

Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101") for the Company's 100% -

owned Cariboo Gold Project ("Cariboo" or the "Project"), located in central British Columbia. The Company

intends to file the Technical Report on SEDAR (www.sedar.com) and on EDGAR (www.sec.gov) under

Osisko Development's issuer profile within 45 days of the date of this news release.

The FS outlines a robust and scalable phased development base case with low initial capital intensity of

$137.3 million and attractive operating costs for the underground development of the Cariboo Gold Project,

producing approximately 1.87 million ounces ("Moz") of gold ("Au") over a 12-year mine life.

Initial production (Phase 1) in the first three years contemplates a 1,500 tonne per day (" tpd") operation

from the Lowhee , Shaft and Mosquito deposits, yielding average annual production of 72, 501 ounces.

Concurrently, underground development will advance to ramp up operations to 4,900 tpd in year four,

increasing average annual production to 193,798 ounces in Phase 2, with potential to scale production

further in the future.

Underground mining will be conducted using highly-mechanized, low-cost bulk tonnage methods designed

to target the extraction of ore contained in gold vein corridors: a high-density network of mineralized quartz

veins hosted mainly within unmineralized sandstone. A pre-concentration ore sorting facility is expected to

significantly improve processed grades by separating non-mineralized material from ore, while substantially

reducing processing volumes, energy costs, and the overall environmental impact footprint of the operation

with fewer tailings, reduced water usage and ability to use waste as backfill.

The Company remains on track for completing the Environmental Assessment (" EA") process early in the

second quarter of 2023 and anticipates receiving final permits by the end of 2023 (see "Permitting" below).

FEASIBILITY STUDY HIGHLIGHTS:

• $502 million after-tax net present value at a 5% discount rate (" NPV5%") (pre-tax $691 million) at

a base case gold price of US$1,700 per ounce ("/oz") and CAD:USD exchange rate of 0.77;

• 20.7% after-tax internal rate or return ("IRR") (pre-tax 24.4%);

• $79 million average annual after-tax free cash flow ("FCF");

• $901 million cumulative after-tax life-of-mine ("LOM") FCF;

• 163,695 ounces ("oz") of Au LOM average annual production;

o 72,501 oz Au Phase 1 (years 1 to 3) average annual production;

o 193,798 oz Au Phase 2 (years 4 to 12) average annual production;

• 1.87 Moz LOM total cumulative gold production;

• 3.78 grams per tonne ("g/t") Au average LOM diluted head grade:

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o 4.43 g/t Au in Phase I (post-ore sorting 8.20 g/t Au);

o 3.72 g/t Au in Phase II (post-ore sorting 6.39 g/t Au);

• 92.0% average LOM recovery rate (93.6% in Phase I, 91.8% in Phase II);

• $102.6 per tonne ("$/t") mined LOM total unit operating costs;

• Probable Mineral Reserves containing 16.7 million tonnes (" Mt") at an average grade of 3.78 g/t

Au for a total of 2.03 Moz of gold;

• US$792/oz Au LOM average cash costs;

• US$968/oz LOM average all-in sustaining costs ("AISC");

• $137.3 million Phase 1 initial capital expenditures (including $10.3 million in contingency costs);

• $451.1 million Phase 2 expansion capital expenditures (including $36.7 million in contingency

costs);

• Peak full labour force (Phase 2) of 550 persons during operations and 635 during expansion

construction.

Sean Roosen, Chair of the Board and CEO of Osisko Development, commented, " This feasibility study

demonstrates that the Cariboo Gold Project will be a large -scale, long-life and profitable gold mine. It will

also produce significant quantities of gold in its initial years at a capital cost below $140 million. By phasing

construction, we have minimized our exposure to development risk at Cariboo, optimized the sequencing

of the ass ets in our portfolio and maximized our ability to scale Cariboo to reach its full potential in the

future. We envision Cariboo as a project that will be a cash flow engine for the company for decades into

the future. Historic mining in the district was focused on individual veins and replacement bodies with grades

in excess of 12 g/t Au , which is consistent with our work completed to date . Once underground, we are

excited to apply our strong understanding of the controls on mineralization to unlock Cariboo’s vast

exploration potential at depth within the current mining zones, which we believe have strong potential to

continue across Cariboo’s 83-kilometer mineralized trends."

Table 1: 2022 Cariboo Feasibility Study Summary Results

METRIC UNIT PHASE 1 PHASE 2 TOTAL LOM

Base Case Assumptions

Gold Price US$/oz 1,700

Exchange Rate CAD:USD 0.77

Discount Rate % 5.0%

Production

Mine Life years 3 9 12

Total Ore Mined tonnes 1,542,471 15,160,983 16,703,454

Average Throughput tpd 1,500 4,900 4,056

Average Gold Head Grade, diluted g/t Au 4.43 3.72 3.78

Total Contained Gold oz 219,488 1,811,665 2,031,152

Average Gold Recovery Rate % 93.6% 91.8% 92.0%

Total Recovered Gold, payable oz 205,419 1,663,436 1,868,856

Average Annual Gold Production oz/year 72,501 193,798 163,695

Unit Operating Costs

Underground Mining $/t mined 77.6 51.1 53.6

Processing $/t mined 37.1 25.3 26.4

Concentrate Transport $/t mined 17.3 3.5 4.8

Water and Waste Management $/t mined 18.4 6.1 7.2

General and Administrative $/t mined 19.4 9.8 10.7

Total Unit Operating Costs $/t mined 169.8 95.8 102.6

Page 3 of 16

METRIC UNIT PHASE 1 PHASE 2 TOTAL LOM

Operating Costs

Total Cash Costs2 US$/oz 1,149 748 792

AISC2 US$/oz 1,634 886 968

Capital Expenditures3

Initial Capital $M 137.3 – 137.3

Expansion Capital $M – 451.1 451.1

Sustaining Capital $M 134.2 332.4 466.6

Total $M 271.5 783.5 1,055.0

Notes:

1. Totals may not add up due to rounding.

2. This is a non-IFRS measure. Refer to "Non-IFRS Financial Measures" at the end of this news release.

3. Capital Expenditures do not include sunk costs ($2.5M) nor pre-permit expenses ($64.8M).

FEASIBILITY STUDY DETAILS

The Cariboo Gold Project is an advanced stage gold exploration project 100%-owned by Osisko

Development located in the historic Wells -Barkerville mining camp, in the District of Wells, central British

Columbia, Canada. The total land package covers an area of 155,000 hectares and includes approximately

80 kilometers strike of mineral targets identified to date.

The FS for the Project was prepared and compiled by BBA , supported by independent consulting firms,

including InnovExplo Inc. ("InnovExplo"), SRK Consulting (Canada) Inc. ( "SRK"), Golder Associates Ltd.

(amalgamated with WSP Canada Inc. on 1 January 2023 to form WSP Canada Inc.) ("Golder"), WSP USA

Inc. ("WSP"), Falkirk Environmental Consultants Ltd. ("Falkirk"), Klohn Crippen Berger Ltd. ("KCB"), KCC

Geoconsulting Inc. ("KCC"), and JDS Energy & Mining Inc. ("JDS"). A complete summary of all contributors

and their respective areas of responsibility is presented under "Technical Information and Qualified

Persons".

Figure 1: Cariboo Gold Project Production Profile

ECONOMIC ANALYSIS

The Company used a base case gold price assumption of US$1,700/oz and a CAD:USD exchange rate of

0.77 in its analysis and incorporated only Probable Mineral Reserves as defined herein. Based on these

Page 4 of 16

assumptions, the Project generates an after -tax NPV5% of $502 million and an after-tax IRR of 20.7% on

an unlevered basis. The FS economics are most sensitive to fluctuations in the following inputs, in order of

magnitude of impact: gold price, operating costs, and capital costs.

Table 2: Summary Economic Results (US$1,700/oz Au)

LOM METRIC UNIT TOTAL LOM

Net Smelter Return (NSR) Revenue $M 4,126

Cumulative Cash Flow (pre-tax)1 $M 1,192

Average Annual Cash Flow (pre-tax)1 $M/year 104

Total Taxes Paid $M 291

Cumulative FCF (after-tax)1 $M 901

Average Annual FCF (after-tax)1 $M/year 79

Pre-tax After-tax

Net Present Value (NPV5%) $M 691 502

Internal Rate of Return (IRR) % 24.4% 20.7%

Payback period years 5.8 5.9

Notes:

1. This is a non-IFRS measure. Refer to "Non-IFRS Financial Measures" at the end of this news release.

Table 3: Economic Sensitivities to Gold Price (Base case in Bold)

Gold Price Assumption (US$/oz)

LOM METRIC UNIT 1,300 1,400 1,500 1,600 1,700 1,800 1,900 2,000

NPV5%, pre-tax $M 38.3 201.4 364.5 527.6 690.6 853.7 1,016.8 1,179.8

NPV5%, after-tax $M -2.9 157.5 284.9 394.5 502.4 609.3 715.1 820.7

IRR, pre-tax % 6.2% 11.0% 15.6% 20.1% 24.4% 28.7% 33.0% 37.3%

IRR, after-tax % 4.9% 9.8% 13.6% 17.2% 20.7% 24.3% 27.8% 31.4%

Payback, pre-tax years 9.0 7.7 6.8 6.2 5.8 5.4 5.1 4.8

Payback, after-tax years 9.5 8.0 7.0 6.3 5.9 5.5 5.2 4.9

Table 4: Economic Sensitivities to Exchange Rate (Base case in Bold)

Exchange Rate Assumption (CAD:USD)

LOM METRIC UNIT 0.90 0.85 0.80 0.77 0.70 0.65 0.60 0.55

NPV5%, pre-tax $M 288.3 427.5 584.1 690.6 964.5 1,198.6 1,471.7 1,794.4

NPV5%, after-tax $M 232.8 327.5 432.1 502.4 681.2 832.8 1,008.6 1,215.7

IRR, pre-tax % 13.5% 17.4% 21.6% 24.4% 31.6% 37.8% 45.2% 54.2%

IRR, after-tax % 12.0% 15.0% 18.4% 20.7% 26.7% 31.8% 38.0% 45.7%

MINERAL RESERVES AND MINERAL RESOURCES

Vein Corridors

Vein Corridors of the Cariboo Gold Project Mineral Resources and Reserves comprise a high-density

network of mineralized quartz veins hosted within unmineralized sandstone. Individual mineralized veins

within these corridors have widths varying from centimeters to several meters ("m") and strike lengths from

a few meters to over 50 m. These corridors have been defined from surface to a vertical depth of 650 m,

averaging 300m, and remain open for expansion at depth and along strike. Gold grades are intimately

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associated with quartz vein -hosted pyrite as well as pyritic, intensely silicified wall rock haloes in close

proximity to the veins.

Mineral Resources Estimate

The FS includes an updated Mineral Resources estimate incorporating an additional 35,578 meters of

drilling data from Shaft, Valley, and Lowhee completed since May 24, 2022 being the effective date of the

technical report titled "Preliminary Economic Assessment for the Cariboo Gold Project, District of Well,

British Columbia, Canada", dated May 24, 2022 for the deposits of Cow Mountain (Cow and Valley Zones),

Island Mountain (Shaft and Mosquito Zones), and Barkerville Mountain (Lowhee and KL Zones). This

resulted in an increase of 6% of total gold ounces in the Inferred Resources category. Measured and

Indicated resources are exclusive of Mineral Reserves. Mineral Resources have an effective date of

November 11, 2022.

Table 5: Cariboo Mineral Resources Statement – November 11, 2022

Classification / Deposit Tonnes

(000's)

Gold Grade

(g/t)

Contained Gold

(000's oz)

Measured – – –

Bonanza Ledge 47 5.06 8

Indicated

Bonanza Ledge 32 4.02 4

BC Vein 1,030 3.12 103

KL 386 3.18 39

Lowhee 1,368 3.18 140

Mosquito 1,288 3.68 152

Shaft 4,781 3.39 523

Valley 2,104 3.14 213

Cow 3,644 3.31 388

Total Indicated 14,635 3.32 1,564

Inferred

BC Vein 461 3.55 53

KL 1,918 2.75 169

Lowhee 445 3.34 48

Mosquito 1,290 3.55 147

Shaft 6,468 3.84 800

Valley 2,119 3.30 225

Cow 2,769 3.03 270

Total Measured & Indicated 14,682 3.33 1,571

Total Inferred 15,470 3.44 1,712

Notes:

1. Mineral Resources are exclusive of Mineral R eserves. Mineral Res ources that are not Mineral Reserves do not have

demonstrated economic viability.

2. The Mineral Resource Estimate conforms to the 2014 CIM Definition Standards on Mineral Resources and Reserves and follows

the 2019 CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines.

3. A total of 481 vein zones were modelled for the Cow Mountain (Cow and Valley), Island Mountain (Shaft and Mosquito),

Barkerville Mountain (BC Vein, KL, and Lowhee) deposits and one gold zone for Bonanza Ledge. A minimum true thickness of

2.0 m was applied, using the Au gold grade of the adjacent material when assayed or a value of zero when not assayed.

4. The estimate is reported for a potential underground scenario at a cut-off grade of 2.0 g/t Au, except for Bonanza Ledge at a cut-

off grade of 3.5 g/t Au. The cut-off grade for the Cow, Valley, Shaft, Mosquito, BC Vein, KL, and Lowhee deposits was calculated

using a gold price of US $1,700/oz; a USD :CAD exchange rate of 1. 27; a global mining cost of $ 54.32/t; a processing and

transport cost of $22.29/t;a G&A plus Environmental cost of $15.31/t; and a sustaining CapEx cost of $31.19/t. The cut-off grade

for the Bonanza Ledge deposit was calculated using a gold price of US $1,700/oz; a USD:CAD exchange rate of 1.27; a global

Page 6 of 16

mining cost of $79.13/t; a processing and transport cost of $65.00/t; and a G&A plus Environmental cost of $51.65/t. The cut-off

grades should be re-evaluated in light of future prevailing market conditions (metal prices, exchange rate, mining cost, etc.).

5. Bulk density varies from 2.69 g/cm3 to 3.20 g/cm3.

6. A four-step capping procedure was applied to composited data. Restricted search ellipsoids ranged from 7 to 50 g/t Au at four

different distances ranging from 25 m to 250 m. High-grades at Bonanza Ledge were capped at 70 g/t Au on 2.0 m composited

data.

7. The gold Mineral Resources for the Cow, Valley, Shaft, Mo squito, BC Vein, KL, and Lowhee vein zones were estimated using

Datamine StudioTM RM 1.9 software using hard boundaries on composited assays. The silver Mineral Resources and the dilution

halo gold mineralization were estimated using Datamine StudioTM RM Pro 1.11. The OK method was used. Mineral Resources

for Bonanza Ledge were estimated using GEOVIA GEMSTM 6.7 software using hard boundaries on composited assays. The OK

method was used to interpolate a block model.

8. Results are presented in situ. Calculations used metric units (met ers, tonnes, g/t). Any discrepancies in the totals are due to

rounding effects.

Mineral Reserves Estimate

Probable Mineral Reserves of 16.7 Mt grading 3.78 g/t Au for 2.03 Moz of contained gold in underground

deposits, as defined below, have an effective date of December 6, 2022 and form the basis of the FS. Only

Mineral Resources that were classified as Measured and Indicated were given economic attributes in the

mine design and when demonstrating economic viability were classified as Mineral Reserves, incorporating

an external mining dilution factor of 8% into the Mineral Reserves estimate.

Table 6: Cariboo Mineral Reserves Statement – December 6, 2022

Classification / Deposit Tonnes

(000's)

Gold Grade

(g/t)

Contained Gold

(000's oz)

Proven – – –

Probable

Cow 4,127 3.41 453

Valley 3,445 3.70 410

Shaft 7,962 3.87 990

Mosquito 603 4.93 95

Lowhee 567 4.56 83

Total Proven and Probable Reserves 16,703 3.78 2,031

Notes:

1. Totals may not add up due to rounding.

2. Mineral Reserves have been estimated in accordance with CIM Definition Standards for Mineral Resources and Mineral

Reserves (2014), which are incorporated by reference in NI 43-101.

3. Mineral Reserves used the following assumptions: US$1,700/oz gold price, USD:CAD exchange rate of 1.27, and variable cut-

off value from 1.70 g/t to 4.00 g/t Au

4. Mineral Reserves include both internal and external dilution along with mining recovery. The external dilution is estimated to be

8%. The average mining recovery factor was set at 93.6% to account for ore left in each block in the margins of the deposit.

CAPITAL COSTS

The FS focu sed on presenting a mine plan consistent with the objective of minimizing the overall

environmental and carbon footprint of the Project on the surrounding communities , leveraging energy

efficient mining technologies, including potential electrification of the full mining fleet, and reducing the

overall economic risk associated with significant capital outlays at the onset of project development. With

this in mind, development and exploitation activities are expected to focus on two distinct phases of

operations.

Initial capital cost for the Project in Phase 1 is estimated at $137.4 million, with total expansion capital costs

in Phase II estimated at $451.1 million, and to be incurred over years 2, 3 and 4. Sustaining capital costs

over the LOM are estimated at $466.6 million. Total cumulative LOM capital costs are estimated at $1,055.1

million, not including site reclamation and closure costs of $17.3 million and estimated salvage value of

$56.2 million. Capital costs for Phase 1 do not include sunk costs ($2. 5 million) or pre-permit expenses

($64.8 million) planned for 2023. The overall capital cost estimate developed in this FS generally meets the

AACE International Class 3 requirements and has an accuracy range of between -10% and +15%. A total

Page 7 of 16

of $10.3 million in contingency capital (P50) was included for Phase 1, representing approximately 12.7%

of initial capital, not including mobile equipment and underground mine development costs.

Table 7: Capital Costs Summary1

Item ($M)

Phase 1 -

Initial

Capital

Phase 2-

Expansion

Capital

Sustaining

Capital Total

Surface Mobile equipment – 0.1 9.3 9.4

Underground mine 53.8 110.8 313.3 478.0

Water and waste management 6.5 12.9 37.3 56.7

Electrical and communications 10.2 31.8 62.9 104.9

Surface infrastructure 1.8 33.0 2.7 37.5

Processing – Mine Site Complex 5.2 114.5 4.4 124.1

Processing – QR Mill 17.5 25.7 – 43.2

Construction indirect costs 10.6 55.6 1.1 67.3

General services 8.7 30.0 27.0 65.7

Pre-production 12.7 – – 12.7

Contingency (P50) 10.3 36.7 8.6 55.6

SUB-TOTAL 137.3 451.1 466.6 1,055.0

Site reclamation and closure – – 17.3 17.3

Salvage value – – (56.2) (56.2)

TOTAL CAPITAL COST 137.3 451.1 427.8 1,016.2

Notes:

1. Capital Expenditures do not include sunk costs ($2.5M) or pre-permitting expenses ($64.8M) which total $67.3M.

OPERATING COSTS

Operating costs estimate includes mining, transportation and ore processing costs to produce gold doré. It

also includes costs for tailings management, water treatment and general and administration expenses.

The average operating cost s over the 12-year mine life is estimated to be $ 102.6 per tonne mined. At its

peak, the mine will emp loy 550 persons during operations (Phase 2) and 63 5 during expansion

construction.

Mining costs are inclusive of backfilling costs without the binder content of the paste bac kfill, which is

included in the processing cost . Processing costs are inclusive of underground crushing costs and

subsequent handling of ore during Phase II of the Project, as well as the costs related to mineral sorting for

both Phase I and II.

Table 8: Operating Costs

Item LOM

($M)

Avg. Cost

($M/year)

Avg. LOM

($/t mined)

Avg. LOM

($/oz)

OPEX

(%)

Underground mining 894.9 78.4 53.6 478.7 52%

Processing 440.4 38.6 26.4 235.6 26%

Concentrate transport 79.5 7.0 4.8 42.5 5%

Water and waste management 120.7 10.6 7.2 64.6 7%

General and administrative 178.8 15.7 10.7 95.7 10%

TOTAL 1,714.4 150.2 102.6 917.0 100%

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Table 9: All-in Sustaining Costs

LOM METRIC TOTAL LOM

($M)

TOTAL LOM

(US$/oz)

Adjusted Operating Costs

Mining costs 894.9 368.2

Processing costs 440.4 181.2

Concentrate transport costs 79.5 32.7

Water and waste management costs 120.7 49.7

General and administration costs 178.8 73.6

Royalties 206.3 84.9

Transport and refining costs 4.8 2.0

Silver by-product credit (0.4) (0.2)

Total Cash Cost2 1,925.1 792.1

LOM sustaining costs 466.6 192.0

Salvage value credit (56.2) (23.1)

Reclamation and closure costs 17.3 7.1

Total All-in Sustaining Costs2 2,352.8 968.1

Notes:

1. Totals may not add up due to rounding.

2. This is a non-IFRS measure. Refer to "Non-IFRS Financial Measures" at the end of this news release.

MINING AND MINE DESIGN

Underground mining is expected to target a total of five mineralized zones over a strike length of 4,400

meters accessed by two underground ramps from the Cow and Valley portals. Each zone comprises several

mineralized vein systems down to a depth of approximately 650 m and is expected to support an initial

1,500 tpd production rate over the first 3 years (Phase 1) before ramping up to 4,900 tpd (pending

permitting) for 9 years (Phase 2).

The b ulk-tonnage long hole mining method was primarily selected given the nature of the sub-vertical

geometry of mineralized veins, the relative lower cost, and the ability to utilize rejected waste rock from ore

sorting as backfill material. Mining dilution is expected to be mitigated with the application of an ore sorting

technology, which is able to cost -efficiently separate gold-bearing ore intimately associated with sulphur

(essentially pyrite) from the lower density unmineralized sandstone rock which is mainly hosting the ore

(see "Processing" section). Although stope strike lengths vary by zone, the minimum designed stope width

for all zones is approximately 3.7 m and stope height approximately 30 m.

Ore will be extracted using a fleet of 10 tonne s scooptram Load Haul Dump and 50 tonne haul trucks and

will be transported to an underground crushing facility where it will be sized and transported to surface for

pre-concentration sorting and flotation via a vertical conveyor.

Underground development will rely on a combination of traditional jumbos and roadheaders. The Company

has previously successfully deployed a roadheader in excavating the Cow portal and one drift in Bonanza

Ledge, demonstrating the amenable nature of the underground rock conditions.

PROCESSING

The processing flowsheet under the initial phase of production is expected to utilize ore sorting and leaching

with a total throughput capacity of 1,500 tpd . In Phase 2, throughput capacity will be expanded to 4,900

tpd, with the addition of a flotation circuit. In the first phase, ore will be initially pre-concentrated using mobile

crushing and ore sorting, which will significantly reduce the overall volume, transportation costs, and overall

footprint of the operation. Following ore sorting, ore will be trucked to the Company's Quesnel River ("QR")

Mill located 116 kilometres from site for further comminution, leaching, and refining. The QR Mill is a fully-