As Canada Votes In 2025 Elections, A Look Back At The Longest-Serving Prime Minister

Canada will vote in its 45th federal election on April 28 to elect a new government, a month after Prime Minister Mark Carney called on Governor General Mary Simon to dissolve the Parliament.

Over the last century-and-a-half, Canada has seen many political stalwarts, but one man stands out - William Lyon Mackenzie King. He served as Canada's Prime Minister for 21 years and 154 days across three non-consecutive terms from 1921 to 1948. 

From navigating the Great Depression to steering Canada through the turbulence of World War II, his tenure remains unparalleled in Canadian history.

Who Was William Lyon Mackenzie King?

Born in Berlin (now Kitchener), Ontario, on December 17, 1874, William Lyon Mackenzie King began his public service early. 

He was appointed to the newly established federal Department of Labour in 1900, where he served as deputy minister and played a key role in arbitrating labour disputes. His efforts led to the creation of the 1907 Industrial Disputes Investigation Act, a landmark in Canadian labour history. 

King's political career took shape when he was elected as a Liberal in North York in 1908, eventually becoming the Minister of Labour in Sir Wilfrid Laurier's Cabinet in 1909.

Though he suffered defeats in the 1911 and 1917 elections, King's political fortunes changed in 1919 when he succeeded Sir Laurier as the leader of the Liberal Party.

In 1921, he became Prime Minister after leading the Liberal Party to victory. His first term was cut short in 1926 due to a political crisis. 

King returned to power in 1926 and served until 1930.

After a period in opposition, he regained the leadership in 1935 and remained in office until his retirement in 1948.

His leadership spanned some of Canada's most transformative years, including the aftermath of the Great Depression, the industrialisation of the country, and much of World War II. By the time King stepped down, Canada had gained greater independence from Britain.

King died in Kingsmere, Quebec, on July 22, 1950.