Municipal elections were held in Ontario, Canada, on October 25, 2010. Voters in Ontario elected mayors, councillors, school board trustees and all other elected officials in all of the province's municipalities. A total of 444 elections were held. Several smaller municipalities in Northern Ontario held no council elections, as their entire councils were acclaimed into office, although the towns still saw contested elections for their school board seats.
Notwithstanding advance polling arrangements, municipal elections were held on the fourth Monday of October. From 1978 until 2006 the second Monday of November was the fixed date.
Candidate registration opened on January 4, 2010 and ended on September 10.
The Legislative Assembly of Ontario legislation (Bill 81, Schedule H), passed in 2006, sets the length of terms in office for all municipal elected officials at four years.
The Toronto municipal election saw an open contest for mayor, due to the retirement of David Miller after two terms. In Ottawa, former MPP and Mayor Jim Watson ran against incumbent Larry O'Brien, who was cleared of bribery charges in 2009.
Some media, including a Sudbury Star editorial which was republished in several other Sun Media newspapers, noted the seeming emergence of a Tea Party mentality in some parts of the province, with a number of self-styled "outsider" or populist candidates – including Rob Ford in Toronto, Joe Fontana in London, David D'Intino in St. Catharines, Rob Matheson in Kingston, Ron Schinners in Sault Ste. Marie and Marianne Matichuk in Greater Sudbury – campaigning on platforms that traded heavily in mistrust of the existing municipal governments.