The Privy Council Office reports directly to the Prime Minister and is headed by the Clerk of the Privy Council and Secretary to the Cabinet. It is both the secretariat for the Cabinet and the Prime Minister's source of public service advice on policy questions and operational issues facing the government, including matters relating to the management of the federation and constitutional development.

The Prime Minister's overall responsibility is to provide leadership to create and sustain the unity of the Ministry required to maintain the confidence of Parliament. The Prime Minister demonstrates this leadership in two distinct ways: through the exercise of unique authorities as head of government; and secondly, through the management and coordination of the government's agenda, as Chair of Cabinet. The core functions of the Clerk of the Privy Council and Secretary to the Cabinet and those of the entire PCO flow directly from these responsibilities. The strength of the PCO is in large measure determined by its ability to concentrate its resources on exclusively supporting these two central responsibilities, in addition to helping the Clerk of the Privy Council and Secretary to the Cabinet fulfill his role as head of the Public Service. The PCO also provides support to the government leaders in the House of Commons and in the Senate, and the President of the Queen's Privy Council and Minister for Intergovernmental Affairs (IGA).

The PCO contributes significantly to the implementation of a clearly articulated agenda of government policy, coordinates timely responses to issues facing the government and the country, and supports the effective operation of the Cabinet and the government. The PCO works to maintain the highest professional and ethical standards in the federal Public Service and to ensure that the Prime Minister and ministers within the Prime Minister's portfolio receive the best quality, consistent, appropriate and non-partisan policy and legal advice, and objective recommendations.

The PCO's core mandate and program activities across the organization are as follows: provide professional, non-partisan policy advice and support to the Prime Minister and portfolio ministers; provide policy advice and secretariat support to Cabinet, Cabinet committees and the Governor in Council; provide overall leadership and direction to the Public Service in support of the government's agenda; and provide commissions of inquiry with administrative and financial support.