As the administrative arm of the Treasury Board, the Secretariat has a dual mandate: to support the Treasury Board as a committee of ministers and to fulfill its statutory responsibilities. These responsibilities derive from the broad authority of sections 5 to 13 of the Financial Administration Act, as well as the authorities in other acts, including the Public Service Labour Relations Act, the Employment Equity Act, the Official Languages Act, the Access to Information Act, the Privacy Act, the Canadian Human Rights Act, the Federal Real Property and Federal Immovables Act, and the Public Service Employment Act. The Secretariat's responsibilities for the general management of the government cross all policy sectors and are managed by 22 operating departments and many other organizational entities as reported in the Main Estimates.

The role of the Secretariat is to define and implement modern governance principles at the federal level. Although accountability for public service management increasingly rests with departments, the Treasury Board and its Secretariat provide strategic leadership in public service management and reform through a management board role. That role emphasizes results-based management and facilitation, essential central controls, and intervention when necessary.

The mission of the Secretariat is to support the Treasury Board and to help the Government of Canada operate effectively using available resources. The Secretariat implements the policies developed by the Treasury Board as the manager of the public service and manages the human, financial, information technology, and material resources that are allocated to it. This is carried out by several branches and sectors of the Secretariat, described below under "Organization."