Endeavour Mining PLC — Proxy Solicitation & Information Statement 2026

Apr 7, 2026

ENDEAVOUR MINING plc

SUPPLEMENT DATED APRIL 7. 2026 TO THE MANAGEMENT INFORMATION CIRCULAR DATED APRIL 7, 2026

The management information circular dated April 7, 2026 (the “Circular”) of Endeavour Mining plc (the “Company”) prepared in connection with the annual general meeting of shareholders of the Company (the “Annual General Meeting”) is hereby amended and supplemented as set out below. All defined terms used in this supplement (the “Supplement”) and not otherwise defined shall have the respective meanings ascribed to them in the Circular, which is available under the Company’s profiles on SEDAR+ at www.sedarplus.ca.

NOTICE-AND-ACCESS

The Company is providing shareholders with access to the Circular for the Annual General Meeting electronically via notice-and-access, instead of mailing out paper copies, as permitted by Canadian securities regulators. This means of delivery is more environmentally friendly as it will help reduce paper use and will also reduce the cost of printing and mailing materials to shareholders.

Electronic copies of the Circular, the Company’s management’s discussion and analysis of the results of operations and financial condition of the Company for the year ended December 31, 2025 and the audited consolidated financial statements of the Company and accompanying notes for the year ended December 31, 2025 together with the auditor’s report thereon and other meeting materials (the “2025 MD&A and Financials”) may be found on SEDAR+ at www.sedarplus.ca and also on the Company’s website at www.endeavourmining.com. Shareholders are reminded to review the Circular before voting.

Shareholders will receive paper copies of a notice package (the “Notice Package”) via pre-paid mail containing a notice with information prescribed by National Instrument 54-101 and a form of proxy (if you are a registered shareholder) or a voting instruction form (if you are a non-registered shareholder).

The Company will not use procedures known as ‘stratification’ in relation to the use of Notice-and-Access Provisions. Stratification occurs when an issuer using Notice-and-Access Provisions sends a paper copy of the Circular to some securityholders with a Notice Package. Shareholders may request paper copies of the Circular and the 2025 MD&A and Financials be sent to them by postal delivery at no cost to them.

Shareholders with questions about notice and access or to request paper copy of the meeting materials can call Computershare toll free at 1-866-962-0498. Any shareholder wishing to obtain a paper copy of the meeting materials should submit their request to Computershare no later than May 11, 2026, in order to receive paper copies of the meeting materials in time to vote before the Meeting.

Under the Notice-and-Access provisions, meeting materials will be available for viewing on the Company’s website for one year from the date of posting.

BY ORDER OF THE BOARD

SAMANTHA CAMPBELL
General Counsel and Company Secretary