A union, in accordance with the Ontario Labour Relations Act, is an organization of employees formed for purposes that include the regulation of relations between employees and employers. This includes a provincial, national, or international trade union, a certified council of trade unions, and a designated or certified employee bargaining agency.

Examples of Unions at York University include the York University Staff Association (YUSA), the Canadian Union of Public Employees (CUPE)

locals 3903 and 1356 and the York University Faculty Association (YUFA).