What is the Prime Minister's main role?

The Prime Minister is the head of the federal government of Canada and the most powerful elected official in Canadian politics. The Prime Minister leads the Cabinet, sets the federal policy agenda, appoints senior officials including federal judges and Crown corporation directors, advises the Governor General on the use of Crown prerogative powers, represents Canada in international affairs, and sets the direction of the federal Public Service. The current Prime Minister is Mark Carney, sworn in March 14, 2025 after winning the Liberal Party leadership.

The office of the Prime Minister is not specifically defined in the Constitution Act, 1867. The role evolved by convention from the British Westminster system. The Prime Minister is the leader of the political party that commands the confidence of the House of Commons (usually the party with the most seats). The Prime Minister is appointed by the Governor General after a federal election and serves until resignation, dismissal (extremely rare), defeat in the House of Commons on a confidence vote, or after losing an election. Prime Ministers may also resign from their party leadership (triggering a leadership convention) but remain Prime Minister until a successor is chosen.

The Prime Minister exercises power through the Prime Minister's Office (PMO, the political staff supporting the Prime Minister), the Privy Council Office (PCO, the non-partisan public service department supporting Cabinet), and the federal departments and agencies. The Prime Minister chairs Cabinet meetings, sets the Cabinet agenda, appoints and dismisses ministers, and is responsible for the overall performance of the federal government. The Prime Minister's advice to the Governor General on the dissolution of Parliament is constitutionally binding except in rare circumstances.

Twenty-four people have served as Prime Minister of Canada since Confederation, beginning with Sir John A. Macdonald (1867 to 1873 and 1878 to 1891). The longest-serving Prime Minister was William Lyon Mackenzie King, who served 21 years over three non-consecutive terms (1921 to 1926, 1926 to 1930, and 1935 to 1948). Kim Campbell (1993) is the only woman to have served as Prime Minister to date. Justin Trudeau (2015 to 2025) was the second person born in office to later serve as Prime Minister (after his father Pierre Trudeau, Prime Minister 1968 to 1979 and 1980 to 1984).