OceanaGold : 2024 RGMP Implementation and Conformance Report

RESPONSIBLE GOLD MINING PRINCIPLES IMPLEMENTATION AND CONFORMANCE REPORT

2024

ACKNOWLEDGEMENT

OceanaGold acknowledges the Indigenous Peoples in all jurisdictions who host our operations and offices. We demonstrate our respect for Indigenous Peoples through our actions and commitments to responsible business practices.

ABOUT THIS REPORT

Reporting boundary and scope

This RGMP Implementation and Conformance Report (Report) summarizes how OceanaGold conformed with the requirements of the World Gold Council's (WGC) Responsible Gold Mining Principles ('RGMPs' or 'Principles') from January 1, 2024 to December 31, 2024.

Unless otherwise stated, references to "OceanaGold", "we" and "our" in this report refer to OceanaGold Corporation (OGC) and our subsidiaries.

For the purposes of this report, the reporting boundary includes all mining and processing operations, as well as the Company's corporate and administrative offices, for which OceanaGold is the majority owner and has direct control. This is consistent with the reporting boundaries that OceanaGold publicly discloses in its annual Sustainability Report.

OceanaGold's operating assets:

• Haile Gold Mine, our wholly owned open pit and underground operation located near Kershaw, South Carolina, United States ("Haile" or "Haile Gold Mine")

• Didipio Mine, our 80%-owned underground gold and copper mine and surface stockpile operation located in Luzon, Philippines ("Didipio" or "Didipio Mine")

• Macraes Operation, our wholly owned open pit and underground operation located in the South Island, New Zealand ("Macraes" or the "Macraes Operation")

• Waihi Operation, our wholly owned underground operation, which includes the proposed Waihi North Project, including the Wharekirauponga Underground development project ("WUG"), and early stage exploration permits of Dome Fields North and South, Twin Hills, and Neavesville, located in the North Island, New Zealand ("Waihi" or the "Waihi Operation")

  OceanaGold's corporate and administrative offices:

• Vancouver, British Colombia, Canada (head office)

• Brisbane, Queensland, Australia

• Melbourne, Victoria, Australia

• Manila, Philippines

• Dunedin, New Zealand

• Singapore

Cautionary statement for public release

This report may contain statements that reflect the current beliefs and expectations of the Company about the future plans and results of the Company as of the respective dates indicated. These forward-looking statements are based

on a number of assumptions about the operations of the Company and factors beyond the control of the Company and are subject to significant risks and uncertainties, and, accordingly, actual results may differ materially from these forward-looking statements contained in this report regarding past trends or activities should not be taken as a representation that such trends or activities will continue in the future. There is no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. You should not

place undue reliance on forward-looking statements, which speak only as of the date of this report. The Company and its advisors have no obligation and do not undertake to revise forward-looking statements contained in this report to reflect future events or circumstances.

This report does not contain all material information concerning the Company or its securities, particularly with respect to the risks and special considerations involved with an investment in any securities of the Company, and the information set forth in this report is subject to change without notice. Certain data in this report was obtained from various external data sources, and the Company has not verified such data with independent sources. The Company is under no obligation to update or keep current the information contained herein.

The information contained in this report has been taken from sources deemed reliable by the Company. However, no representation or warranty (whether express or implied) is made as to the fairness, accuracy, completeness, or correctness of, and no reliance should be placed on, such information or opinions contained herein. None of the Company, any of its advisors or any of its affiliates or any of its directors, officers, employees, advisers, or representatives shall have any liability whatsoever (for

negligence or misrepresentation or in tort or under contract or otherwise) for any loss howsoever arising from any use of information presented in this report or otherwise arising in connection with this report.

FEEDBACK

We invite feedback on this report or any aspect of our sustainability performance via [e-mail].

For enquiries, please visit the "Contact Us" section of our

website at oceanagold.com

Front cover: Our drilling team prepare to start work underground at our Haile Gold Mine, USA

OUR BUSINESS

OceanaGold is a multinational gold and copper producer with four producing mines. Our head office is in Vancouver (Canada), and we have support offices in Brisbane and Melbourne (Australia), Manila (Philippines), Singapore and Dunedin (New Zealand).

DIDIPIO MINE

Luzon Island, Philippines

WAIHI OPERATION

North Island, New Zealand

OCEANAGOLD HEAD OFFICE

Vancouver

HAILE GOLD MINE

South Carolina, USA

MACRAES OPERATION

South Island, New Zealand

DIDIPIO MINE

Location: Luzon Island, Philippines

Profile: Underground operation producing gold and silver as doré bars and gold/copper in concentrate

2024 production: 97koz Gold, 149koz Silver and 12kt Copper Employees and Contractors as at December 31, 2024:

Employees: 822

Contractors: 1,249

MACRAES OPERATION

Location: South Island, New Zealand

Profile: Open pit and underground operation producing

gold as doré bars

2024 production: 125koz Gold and 4koz Silver Employees and Contractors as at December 31, 2024:

Employees: 672

Contractors: 133

WAIHI OPERATION

Location: North Island, New Zealand

Profile: Underground operation producing gold and silver as doré bars

2024 production: 53koz Gold and 193koz Silver Employees and Contractors as at December 31, 2024:

Employees: 427

Contractors: 144

HAILE GOLD MINE

Location: South Carolina, USA

Profile: Open pit and underground operation producing gold

and silver as doré bars

2024 production: 212koz Gold and 131koz Silver Employees and Contractors as at December 31, 2024:

Employees: 769

Contractors: 271

OVERVIEW

OceanaGold Corporation is a multi-national, mid-tier gold producer head-quartered in Vancouver, Canada with four operating mines and a pipeline of organic growth projects.

Our Purpose is mining gold for a better future. We care about the impact of our operations and use safe and responsible practices to continuously improve how we operate while minimizing negative impacts.

Our Vision is to be a company people trust, want to work and partner with, supply and invest in, to create value. Running our business safely and responsibly is key to our success.

It helps us create long-term value and sustainable results at every stage, from exploration to operations and closure.

OUR COMMITMENT TO THE RESPONSIBLE GOLD MINING PRINCIPLES

At OceanaGold, we are committed to mining safely and responsibly. We strive to operate with respect for the environment and the human rights and wellbeing of our employees, contractors and members of the communities associated with our activities.

OceanaGold takes this commitment seriously. As such, we have committed to implementing and conforming with, the World Gold Council's (WGC) Responsible Gold Mining Principles (RGMPs) to embed responsible gold mining practices in our operations and annually disclose the status of OceanaGold's conformance with the RGMPs, including instances of non-conformance.

We believe that, coupled with good governance, responsible mining delivers benefits for host countries and local communities. It contributes to socio-economic development through increasing prosperity, providing jobs and supply chain opportunities, and raising technical standards through innovation and building skills.

This RGMP Implementation and Conformance Report summarizes how we have conformed with the requirements of the RGMPs for the year-ended December 31, 2024.

Our conformance has been independently assured by

PricewaterhouseCoopers (PwC).

Our Chief Sustainability Officer is responsible for overseeing conformance with the RGMPs. This role reports directly to our Chief Executive Officer and provides regular updates

on Sustainability matters to the Board Sustainability Committee.

DESCRIPTION OF KEY ACTIVITIES AND ACHIEVEMENTS IN 2024

To further embed and underpin the implementation of the

RGMPs, including into our business, in 2024 we have:

• Developed and published a Company-wide Supplier Code

  of Conduct. The Supplier Code of Conduct, approved by our CEO, has been published on our website in both English and Tagalog, and directly communicated to our suppliers and contractors.

• Reviewed and updated our Responsible Mining Policies. Five sustainability policies included within the Responsible Mining Framework, and 10 Statements of Position, were reviewed and consolidated to create four new updated, Board approved policies: Health & Safety Policy, Environment Policy, Human Rights Policy and External Affairs & Social Performance Policy.

• Developed, implemented and maintained policies, systems, processes and controls to ensure we conform with the RGMPs across our operations.

• Disclosed information that helps external stakeholders understand how we achieve conformance with the RGMPs including our annual Sustainability Report, Modern Slavery Statement and supporting information;

• Obtained an independent assessment and limited assurance of our implementation and conformance with the RGMPs (including confirmation that our Conflict Free Gold Statement, meets the requirements of RGMP Principle 5: Human Rights and Conflict).

Water treatment plant at our Waihi Operation, New Zealand

CONFORMANCE STATUS

To the best of our knowledge, and with reference to the findings of PwC's RGMP Conformance Assessment, OceanaGold demonstrated overall conformance with the requirements of the WGC's Responsible Gold Mining Principles in 2024.

TABLE 1 - Summary of OceanaGold's 2024 RGMP conformance status (31 December 2024)

PRINCIPLE FINDINGS AND NOTES

PRINCIPLE 2: UNDERSTANDING OUR IMPACTS

OceanaGold has demonstrated overall conformance with the requirements of Principle 2 encompassing subprinciples 2.1 to 2.5.

PRINCIPLE 4: SAFETY & HEALTH

OceanaGold has demonstrated overall conformance with the requirements of Principle 4 encompassing subprinciples 4.1 to 4.4.

PRINCIPLE 6: LABOUR RIGHTS

OceanaGold has demonstrated overall conformance with the requirements of Principle 6 encompassing subprinciples 6.1 to 6.7.

PRINCIPLE 8: ENVIRONMENTAL STEWARDSHIP

OceanaGold has demonstrated overall conformance with the requirements of Principle 8 encompassing subprinciples 8.1 to 8.5.

PRINCIPLE 10: WATER, ENERGY AND CLIMATE CHANGE

OceanaGold has demonstrated overall conformance with the requirements of Principle 10 encompassing subprinciples 10.1 to 10.4

PRINCIPLE 1: ETHICAL CONDUCT

OceanaGold has demonstrated overall conformance with the requirements of Principle 1 encompassing subprinciples 1.1 to 1.7.

PRINCIPLE 3: SUPPLY CHAIN

OceanaGold has demonstrated overall conformance with the requirements of Principle 3 encompassing subprinciples 3.1 to 3.4.

PRINCIPLE 5: HUMAN RIGHTS AND CONFLICTS

OceanaGold has demonstrated overall conformance with the requirements of Principle 5 encompassing subprinciples 5.1 to 5.4.

PRINCIPLE 7: WORKING WITH COMMUNITIES

OceanaGold has demonstrated overall conformance with the requirements of Principle 7 encompassing subprinciples 7.1 to 7.8.

PRINCIPLE 9: BIODIVERSITY, LAND USE AND MINE CLOSURE

OceanaGold has demonstrated overall conformance with the requirements of Principle 9 encompassing subprinciples 9.1 to 9.4.

In accordance with the requirements of the WGC's Conflict-Free Gold Standard, OceanaGold has prepared an annual Conflict-Free Gold Statement for the 2024 year of operation. This Statement supports our conformance with RGMP Principle 5: Human Rights and Conflict, and has also been independently assured by PwC.

INDEPENDENT ASSURANCE

In November 2024, PwC evaluated our continued implementation and conformance with the RGMPs. The assessment included a review of how the RGMPs are integrated with our governance systems, policy documents, standards and guidelines, and site verification at our Waihi Operation to confirm their application in practice. Supplementary conformance testing was conducted at all the remaining operations in line with the WGC "Guidance on Implementing and Assuring the RGMPs".

PwC's Independent Assurance Report relating to OceanaGold's implementation and conformance with the RGMPs in 2024,

and of this report, follows in Appendix 1.