Mr. Steeve Lavoie reports

FIRST PHOSPHATE FILES NI 43-101 TECHNICAL REPORT FOR UPDATED MINERAL RESOURCE ESTIMATE FOR BÉGIN-LAMARCHE IGNEOUS PHOSPHATE DEPOSIT

First Phosphate Corp. has filed its updated mineral resource estimate (MRE) technical report for the Begin-Lamarche project located 50 kilometres northwest of the city of Saguenay, Que., Canada.

The technical report titled "Technical Report and Updated Mineral Resource Estimate of The Begin-Lamarche Phosphate Property, Saguenay - Lac Saint-Jean Region, Northern Quebec," dated Aug. 24, 2026, with an effective date of May 1, 2026, was prepared by P&E Mining Consultants Inc. in accordance with National Instrument 43-101 -- Standards of Disclosure for Mineral Projects and supports the disclosures made by the company in its news release dated May 26, 2026. A full copy of the report is available on the First Phosphate website and can be found at SEDAR+ under the company's issuer profile.

MRE highlights include:

• The updated MRE includes a 378-per-cent increase in indicated mineral resources over the company's initial MRE dated Sept. 9, 2024;
• Measured pit-constrained mineral resource: 6.2 Mt (million tonnes) at 7.70 per cent P2O5 (phosphate);
• Indicated pit-constrained mineral resource: 198.5 Mt at 6.00 per cent P2O5;
• Inferred pit-constrained mineral resource: 89.5 Mt at 6.16 per cent P2O5.
• The deposit remains open at depth.
• Metallurgical testwork indicates an anticipated apatite concentrate grade of 40.4 per cent P2O5 at an 88-per-cent process recovery rate, with very low levels of potentially deleterious elements and has been qualified for production of battery-grade phosphoric acid for lithium iron phosphate (LFP) battery with a conversion ratio of 91.1 per cent.
• The deposit is located next to existing road and hydroelectric infrastructure and at only 70 kilometres driving distance from the deep-sea Port of Saguenay.
• The deposit benefits from definitive, long-term, partially prepaid offtake from an existing, creditworthy partner.
• Apatite (phosphorus, phosphate) is listed on the critical minerals lists of Quebec, Canada, the United States and the European Union.

Qualified person

The qualified person, independent of the issuer, responsible for estimating the mineral resources of the Begin-Lamarche property, within the meaning of National Instrument 43-101, is Antoine Yassa, PGeo, of the firm P&E Mining Consultants Inc. Mr. Yassa has read this press release and confirms that the scientific and technical information in this press release for accuracy and compliance with NI 43-101.

The scientific and technical disclosure for First Phosphate included in this news release have been reviewed and approved by Steeve Lavoie, PGeo. Mr. Lavoie is chief geologist of the company and a qualified person under National Instrument 43-101 -- Standards of Disclosure of Mineral Projects.

About First Phosphate Corp.

First Phosphate is a mineral exploration and development and clean technology company dedicated to building and reshoring a vertically integrated mine-to-market supply chain for the production of LFP batteries in North America. Target markets include energy storage, data cenres, robotics, mobility and national security. First Phosphate's flagship Begin-Lamarche property, located in Saguenay-Lac-Saint-Jean, Que., Canada, represents a rare North American igneous phosphate resource producing high-purity phosphate characterized by very low levels of impurities.

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