Premiership of Justin Trudeau

The premiership of Justin Trudeau began on November 4, 2015, when the first Cabinet headed by Justin Trudeau was sworn in by Governor General David Johnston. Trudeau was invited to form the 29th Canadian Ministry and become Prime Minister of Canada following the 2015 federal election, where Trudeau led his Liberal Party to win a majority of seats in the House of Commons of Canada, defeating the Conservative majority government of Prime Minister Stephen Harper. Trudeau's Liberals were reduced to minority governments in the federal elections of 2019 and 2021, with his party losing the national popular vote twice.

On March 14, 2025, Trudeau resigned as prime minister, being succeeded by Mark Carney.

Justin Trudeau's Liberal Party won the 2015 Canadian federal election with 6,943,276 votes, representing 39.47% of votes cast. In the following election in 2019, Justin Trudeau's Liberals won the most seats, but with fewer votes than Andrew Scheer's Conservative Party. The Liberals received 6,018,728 votes (33.12%) compared to the Conservatives' 6,239,227 (34.34%). In the following election in 2021, Justin Trudeau's Liberals won the most seats, but again with fewer votes than Erin O'Toole's Conservative Party. The Liberals received 5,556,629 votes (32.62%) compared to the Conservatives' 5,747,410 (33.74%).

In the federal election of October 19, 2015, the Liberal Party, led by Justin Trudeau, won 184 seats in the 42nd Canadian Parliament and formed a majority government. Trudeau and his Cabinet were sworn in on November 4, 2015. The Conservative Party, led by incumbent prime minister Stephen Harper, won 99 seats, becoming the Official Opposition. Harper had served as prime minister from 2006 to 2015. Trudeau decided to reside at Rideau Cottage rather than 24 Sussex Drive as prime minister.

In the federal election of October 21, 2019, the Liberals, led by incumbent prime minister Justin Trudeau, won 157 seats in the 43rd Canadian Parliament, losing 20 seats from 2015 and thus formed a minority government. The Conservatives, led by Andrew Scheer, won 122 seats, gaining 26 from 2015, and also won the popular vote. The Bloc Québécois, led by Yves-François Blanchet, won 32 seats, gaining 10 from 2015, and attained third-party status in the House of Commons. The New Democratic Party (NDP), under Jagmeet Singh, won 24 seats, losing 15 from 2015. The Green Party, led by Elizabeth May, won 3 seats, gaining 2 from 2015.

In the federal election of September 20, 2021, the Liberals, led by incumbent prime minister Justin Trudeau, won 160 seats in the 44th Canadian Parliament, gaining 3 seats from 2019 and thus formed another minority government. The Conservatives, led by Erin O'Toole, won 119 seats, losing 2 from 2019 and also won the popular vote. The Bloc Quebecois, led by Yves-François Blanchet, won 32 seats and remained "third-party status in the House of Commons". The New Democratic Party (NDP), under Jagmeet Singh, won 25 seats, gaining 1 seat from 2019. The Green Party, led by Annamie Paul, won 2 seats, losing 1 from 2019.

Following the November 4, 2015 Rideau Hall swearing in ceremony by Governor General David Johnston, Justin Trudeau, was invited to form his Cabinet and to become the 23rd Prime Minister of Canada. The Liberal Party, led by Trudeau, won a majority of the seats in the House of Commons of Canada, defeating the Conservative led by Prime Minister Stephen Harper. The original members of the 29th Canadian Ministry included fifteen men and fifteen women and was the first gender-balanced cabinet in Canadian history. Following the July 2018 cabinet shuffle, the cabinet consisted of 34 members with 17 women and 17 men, excluding Trudeau.

Trudeau has promised to decentralize power from the Prime Minister's Office and give Cabinet a larger role in governing, stating "government by cabinet is back".