List of premiers of Ontario by time in office

This is a list of Premiers of Ontario in order of time served in office as Premier of Ontario as of April 25, 2024. The preceding Premier always stays in office during an election campaign, and that time is included in the total. See also List of Ontario political parties by time in office.

Rank	Premier	Incumbency	Dates in Power	Mandates
1	Oliver Mowat		1872-1896	6
2	Bill Davis		1971-1985	4
3	Leslie Frost		1949-1961	3
4	James Whitney		1905-1914	4
5	John Robarts		1961-1971	2
6	Dalton McGuinty		2003-2013	3
7	Mitchell Hepburn		1934-1942	2
8	Howard Ferguson		1923-1930	3
9	Mike Harris		1995-2002	2
10	George William Ross		1899-1905	1
11	David Peterson		1985-1990	1
12	George A. Drew		1943-1948	3
13	William Howard Hearst		1914-1919	0
14	Bob Rae		1990-1995	1
15	John Sandfield Macdonald		1867-1871	1
16	Ernest Charles Drury		1919-1923	1
17	George Stewart Henry		1930-1934	0
18	Arthur Sturgis Hardy		1896-1899	1
19	Kathleen Wynne (incumbent)		2013–present	1
20	Ernie Eves		2002-2003	0
21	Edward Blake	days	1871-1872	1
22	Gordon Daniel Conant	days	1942-1943	0
23	Thomas Laird Kennedy	days	1948-1949	0
24	Frank Miller	days	1985	1
25	Harry Nixon	days	1943	0

^* Frank Miller's Progressive Conservative Party won a plurality of seats in the Ontario general election, 1985, but the resulting 33rd Parliament of Ontario passed a motion of no confidence against him less than two months into his mandate, replacing his government with David Peterson's Liberal Party. This table counts the 1985 election as a mandate for Miller.