This is a list of the premiers of the province of Ontario, Canada, since Confederation in 1867. Ontario uses a unicameral Westminster-style parliamentary government, in which the premier is the leader of the party that controls the most seats in the Legislative Assembly. The premier is Ontario's head of government, while the Queen of Canada is its head of state and is represented by the Lieutenant Governor of Ontario. The premier picks a cabinet from the elected members to form the Executive Council of Ontario, and presides over that body.

Members are first elected to the legislature during general elections. General elections must be conducted every four years from the date of the last election. An election may also happen if the Governing party loses the confidence of the legislature, by the defeat of a supply bill or tabling of a confidence motion.

This project only covers the time since the Canadian Confederation was created in 1867.

Progressive Conservative Party of Ontario Premier

• John Sandfield MacDonald (16 July 1867 to 20 December 1871)

Ontario Liberal Party Premiers

• Edward Blake (20 December 1871 to 25 October 1872)
• Sir Oliver Mowat (25 October 1872 to 21 July 1896)
• Arthur Sturgis Hardy (21 July 1896 to 21 October 1899)
• Sir George William Ross (21 October 1899 to 8 February 1905)

Progressive Conservative Party of Ontario Premiers

• Sir James Whitney (8 February 1905 to 25 September 1914)
• Sir William Hearst (2 October 1914 to 14 November 1919)

United Farmers of Ontario Premier

• Ernest Drury (14 November 1919 to 16 July 1923)

Progressive Conservative Party of Ontario Premiers

• George Howard Ferguson (16 July 1923 to 15 December 1930)
• George Stewart Henry (15 December 1930 to 10 July 1934)

Ontario Liberal Party Premiers

• Mitchell Hepburn (10 July 1934 to 21 October 1942)
• Gordon Daniel Conant (21 October 1942 to 18 May 1943)
• Harry Nixon (18 May 1943 to 17 August 1943)

Progressive Conservative Party of Ontario Premiers

• George A. Drew (17 August 1943 to 19 October 1948)
• Thomas Laird Kennedy (19 October 1948 to 4 May 1949)
• Leslie Frost (4 May 1949 to 8 November 1961)
• John Robarts (8 November 1961 to 1 March 1971)
• Bill Davis (1 March 1971 to 8 February 1985)
• Frank Miller (8 February 1985 to 26 June 1985)

Ontario Liberal Party Premier

• David Peterson (26 June 1985 to 1 October 1990)

Ontario New Democratic Party Premier

• Bob Rae (1 October 1990 to 26 June 1995)

Progressive Conservative Party of Ontario Premiers

• Mike Harris (26 June 1995 to 14 April 2002)
• Ernie Eves (14 April 2002 to 22 October 2003)

Ontario Liberal Party Premiers

• Dalton McGuinty (23 October 2003 to 11 February 2013)
• Kathleen Wynne (11 February 2013 to 29 June 2018)

Progressive Conservative Party of Ontario Premier

• Doug Ford (29 June 2018 to present)