The Ontario Teachers' Pension Plan Board (French: Régime de retraite des enseignantes et des enseignants de l'Ontario)[5] is an independent organization responsible for administering defined-benefit pensions for school teachers of the Canadian province of Ontario.

Ontario Teachers' is headquartered in Toronto, with regional offices in London, New York, Hong Kong, Singapore, and Mumbai.

[13] One of Canada's largest institutional investors, Ontario Teachers' reported having $249.8 billion in net assets as of June 30, 2023.

[15] In 2001, Ontario Teachers' Pension Plan and Caisse de dépôt et placement du Québec were the sole two investors in a US$360 million fund raised by Canadian company Cordiant Capital.

[16] Ontario Teachers' also owned Camelot Group PLC, which held an exclusive licence to operate the UK National Lottery until January 31st 2024.

[24] Following FTX's collapse in early November 2022, Ontario Teachers' stated that it will write off the entirety of its US$95 million investment by the end of 2022.

[25] On June 6, 2018, a group of global institutional investors, led by Ontario Teachers' and CDPQ, in collaboration with the Government of Canada, announced a project to advance key G7 objectives.

[26] Partner Institutions AIMCo, Allianz, Aviva, CalPERS, CDPQ, Generali, Natixis Investment Managers, OMERS, Ontario Teachers', OPTrust, and PGGM pledged to commit resources, expertise and networks to three initiatives: enhancing expertise in infrastructure financing and development of emerging and frontier economies; opening opportunities for women in finance and investment worldwide; and speeding up the implementation of uniform and comparable climate-related disclosures under the FSB-TCFD framework.