Private Placement for Gross Proceeds up to C$14m

• LAW BY VIRTUE OF THE EUROPEAN UNION (WITHDRAWAL) ACT 2018 (AS AMENDED).

Orosur Announces Brokered Private Placement for Gross Proceeds of up to C$14.0 Million

NOT FOR DISTRIBUTION TO U.S. NEWS WIRE SERVICES OR DISSEMINATION IN THE UNITED STATES.

London, September 23, 2026. Orosur Mining Inc. (“Orosur” or the “Company”) (TSX-V/AIM:OMI) is pleased to announce that it has entered into an agreement with Red Cloud Securities Inc. (the “Agent”), to act as sole agent and bookrunner, together with U.K. corporate brokers Turner Pope Investments (TPI) Ltd. (“Turner Pope”) and Greenwood Capital Partners Limited (“Greenwood”, and together with Turner Pope, together the “U.K. Brokers”), in connection with a best efforts private placement (the “Base Offering”) for gross proceeds of up to C$14,000,000 from the sale of up to 43,750,000 units of the Company (the “Units”) at a price of C$0.32 (being approximately GBP £0.17 at an exchange rate of GBP £0.5328 to C$1.00) per Unit (the “Offering Price”).

Each Unit will consist of one common share of the Company (each, a "Common Share") and one-half of one common share purchase warrant (each whole warrant, a "Warrant"). Each whole Warrant shall entitle the holder to purchase one common share of the Company (each, a "Warrant Share", and the Warrant Shares underlying the Warrants together with the Common Shares to be referred to as the “Underlying Securities”) at a price of US$0.32 (being approximately C$0.45 at an exchange rate of US$0.7109 to C$1.00 and approximately GBP £0.24 at the exchange rate noted above) at any time during the period beginning on the date that is 61 days following the Closing Date as hereinafter defined) and ending on the date which is 24 months following the Closing Date (as herein defined).

The Company has also granted the Agent the option, exercisable in full or in part, up to 48 hours prior to the Closing Date, to sell up to an additional 6,250,000 Units at the Offering Price for up to an additional C$2,000,000 in gross proceeds (the "Agent’s Option", and together with the Marketed Offering, the “Offering”).

The Company intends to use the net proceeds of the Offering principally to advance the Company's Anzá exploration project in Colombia as well as for general working capital and corporate purposes.

The Offering is scheduled to close on or around October 6, 2026 (the “Closing Date”), or such other date as the Company and the Agent may agree and is subject to certain conditions including, but not limited to, receipt of all necessary approvals including the approval of the TSX Venture Exchange (“TSX-V”) and admission of the Common Shares to the AIM Market of London Stock Exchange plc (“AIM”).

The Offering will allow the Company to make use of its joint listing on the TSX-V and AIM to broaden its shareholder base, including institutional investors in Canada, the U.K. and certain other foreign jurisdictions, and is expected to improve the liquidity of the Common Shares.

There is an offering document (the “Offering Document”) related to the Offering in Canada that can be accessed under the Company’s profile at www.sedarplus.ca and on the Company’s website at www.orosur.ca. Prospective investors in Canada should read the Offering Document before making an investment decision.

The U.K. Placing

The element of the Offering which shall be undertaken by the U.K. Brokers in the U.K., shall be carried out by way of a placing (“Placing”) to institutional and other eligible investors. The Company and the U.K. Brokers have entered into a placing agreement with the Company under which, on the terms and subject to the conditions set out in the placing agreement, the U.K. Brokers, as agents for and on behalf of the Company, have agreed to use their respective reasonable endeavours to procure placees in the U.K. for the Units at the Offering Price. The Placing is not being underwritten by the U.K. Brokers or any other person.

The timing of the closing of the book and allocations are at the discretion of the U.K. Brokers and the Agent, in consultation with the Company. Details of the total number of Units, together with any Units which may be issued pursuant to the Agent’s Option (together “Offered Units”), will be announced as soon as practicable after the close of the Offering via a ‘Results of Placing’ announcement.

Admission and Total Voting Rights

Application will be made for the Common Shares underlying the Offered Units to be admitted to trading on AIM (“Admission”). It is expected that Admission will become effective on or around October 7, 2026.

Assuming the issue of up to 43,750,000 Offered Units, which, on Admission, will rank pari passu with the existing Common Shares, and after the inclusion of 1,191,250 Common Shares issued as a result of recent warrant exercises, the total number of Common Shares in issue with voting rights in the Company will be 445,946,324. There are no shares held in treasury.

About Orosur Mining Inc.

Orosur Mining Inc. (TSXV: OMI; AIM: OMI) is a minerals explorer and developer currently operating the Anza Project in Antioquia, Colombia and El Pantano in Santa Cruz, Argentina.

About the Anzá Project

Anzá is a gold exploration project (“Anzá Project”), comprising several exploration licences, and a number of exploration licence applications totalling approximately 530km2 in the prolific Mid-Cauca belt of Colombia.

The Anzá Project is wholly-owned by Orosur via its subsidiaries, Minera Anzá S.A. and Minera Monte Aguila S.A.S.

The Anzá Project is located 50km west of Medellin and is easily accessible by all-weather roads and boasts excellent infrastructure including water, power, communications and large exploration camp.