The prime minister of Canada is the head of government of Canada. Under the Westminster system, the prime minister governs with the confidence of a majority of the elected House of Commons; as such, the prime minister typically sits as a member of Parliament (M.P.) and leads the largest party or a coalition of parties. As first minister, the prime minister selects ministers to form the Cabinet.
Not outlined in any constitutional document, the prime minister is appointed by the monarch's representative, the governor general, and the office exists per long-established convention. Constitutionally, executive authority is vested in the monarch (who is the head of state), but the powers of the monarch and governor general are nearly always exercised on the advice of the Cabinet, which is collectively responsible to the House of Commons. Canadian prime ministers are appointed to the Privy Council and styled as the Right Honourable (French: le très honorable), a privilege maintained for life.
The prime minister is supported by the Prime Minister's Office and heads the Privy Council Office. The prime minister also selects individuals for appointment as governor general, provincial lieutenant governors, territorial commissioners, as well as to the Senate of Canada, Supreme Court of Canada, other federal courts, and senior members of the military and public service.
Mark Carney is the current prime minister of Canada, taking office on March 14, 2025. Since Canadian Confederation in 1867, 24 prime ministers have formed 30 ministries.
The position of prime minister is not outlined in any Canadian constitutional document and is mentioned only in a few sections of the Constitution Act, 1982, and in the Letters Patent, 1947 issued by King George VI. The office and its functions are instead governed by constitutional conventions and modelled on the same office in the United Kingdom.
In 2008, a public-opinion survey showed that 51 per cent of Canadians believed they voted to directly elect the prime minister. In fact, the prime minister, along with the other ministers in Cabinet, is appointed by the governor general on behalf of the monarch. By the conventions of responsible government, the foundation of parliamentary democracy, the governor general will call to form a government the individual most likely to receive the support, or confidence, of a majority of the directly elected members of the House of Commons; as a practical matter, this is often the leader of the party, or a coalition of parties, whose members form a majority, or a very large plurality, of seats in the House of Commons. No document is needed to begin the appointment; both the invitation and acceptance are usually oral.
A prime minister who has given intention to resign may advise the governor general on whom to appoint as the next prime minister. However, if the prime minister is resigning because he or she has lost the confidence of the House of Commons, the viceroy is not obligated to follow that advice. If the leader of the opposition is unable or unwilling to form a government, the governor general can consult whomever he or she wishes.
While there is no legal requirement for the prime minister to be an M.P., for practical and political reasons the prime minister is expected to win a seat very promptly. However, in rare circumstances, individuals who are not sitting members of the House of Commons have been appointed to the position of prime minister. Two former prime ministers—John Joseph Caldwell Abbott and Mackenzie Bowell—served in the 1890s while members of the Senate. Both, in their roles as government leader in the Senate, succeeded prime ministers who had died in office—John A. Macdonald in 1891 and John Sparrow David Thompson in 1894.
Prime ministers who are not M.P.s upon their appointment (or who lose their seats while in office) have since been expected to seek election to the House of Commons as soon as possible. For example, William Lyon Mackenzie King, after losing his seat in the 1925 federal election and again in the 1945 Canadian federal election (despite his party being elected government both times), briefly governed without a seat in the House of Commons on both occasions before winning a by-election a few weeks later. Similarly, John Turner replaced Pierre Trudeau as leader of the Liberal Party in 1984 and subsequently was appointed prime minister while not holding a seat in the House of Commons; Turner won a riding in the next election, but the Liberal Party was swept from power.
When a prime minister loses his or her seat in the legislature, or should a new prime minister be appointed without holding a seat, the typical process that follows is that a member in the governing political party will resign to allow the prime minister to run in the resulting by-election. A safe seat is usually chosen; while the Liberal and Conservative parties generally observed a practice of not running a candidate against another party's new leader in the by-election, the New Democratic Party and smaller political parties typically do not follow the same practice. However, if the governing party selects a new leader shortly before an election is due, and that new leader is not a member of the legislature, they will normally await the upcoming election before running for a seat in Parliament.
The prime minister serves at His Majesty's pleasure, meaning the post does not have a fixed term, and once appointed and sworn in by the governor general, the prime minister remains in office until he or she resign, is dismissed, or dies.
While the life-span of a parliament is constitutionally limited to five years, a 2007 amendment to the Canada Elections Act, Section 56.1(2) limited the term of a Parliament to four years, with election day being set as the third Monday in October of the fourth calendar year after the previous polling date. The governor general may still, on the advice of the prime minister, dissolve parliament and issue the writs of election prior to the date mandated by the constitution or Canada Elections Act; the King–Byng Affair was the only time since Confederation that the governor general refused the prime minister's request for a general vote.
Following parliamentary dissolution, should the prime minister's party subsequently win a majority of seats in the House of Commons, it is unnecessary to reappoint the prime minister or for the prime minister to retake the oath of office. If, however, an opposition party wins a majority of seats, the prime minister may resign or choose to meet Parliament to see if the incumbent government can win a confidence vote. Should the prime minister's party achieve a minority while an opposition party wins a plurality (i.e., more seats than any other party but less than a majority), the prime minister can attempt to maintain the confidence of the House by forming a coalition with other minority parties, which was last entertained in 1925 or by entering into a confidence-and-supply agreement, or by winning support of other parties on a vote-by-vote basis.
Because the prime minister is, in practice, the most politically powerful member of the Canadian government, he or she is sometimes erroneously thought to be Canada's head of state, when in fact that role belongs to the Canadian monarch, represented by the governor general. The prime minister is instead the head of government and is responsible for advising the Crown on how to exercise much of the royal prerogative and its executive powers, which are governed by the written constitution and constitutional conventions. However, the function of the prime minister has evolved with increasing power. Today, per the doctrines of constitutional monarchy, the advice given by the prime minister is ordinarily binding, meaning the prime minister effectively carries out those duties ascribed to the sovereign or governor general, leaving the latter to act in predominantly ceremonial fashions. As such, the prime minister, supported by the Office of the Prime Minister (P.M.O.), controls the appointments of many key figures in Canada's system of governance, including the governor general, the Cabinet, justices of the Supreme Court, senators, heads of Crown corporations, ambassadors and high commissioners, the provincial lieutenant governors, and approximately 3,100 other positions. Further, the prime minister plays a prominent role in the legislative process—with the majority of bills put before Parliament originating in the Cabinet.