The Ontario federal electoral districts each elect one representative to the House of Commons. These districts are defined by Elections Canada. Their boundaries are also used for provincial electoral districts, with exceptions in Northern Ontario.
The following electoral districts are currently represented in the House of Commons.
The House of Commons of Canada is the lower house of the Parliament of Canada. Together with the Crown and the Senate of Canada, they comprise the bicameral legislature of Canada.
Stormont—Dundas—South Glengarry is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1968.
An electoral district in Canada is a geographical constituency upon which Canada's representative democracy is based. It is officially known in Canadian French as a circonscription but frequently called a comté (county). In Canadian English it is also colloquially and more commonly known as a riding or constituency.
Cambridge is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1979.
Newmarket—Aurora is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 2004.
Canada holds elections for legislatures or governments in several jurisdictions: for the federal (national) government, provincial and territorial governments, and municipal governments. Elections are also held for self-governing First Nations and for many other public and private organizations including corporations and trade unions. Municipal elections can also be held for both upper-tier and lower-tier governments.
Leeds—Grenville—Thousand Islands and Rideau Lakes is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons since 1979. Prior to the 2015 election, the riding was known as Leeds—Grenville.
Etobicoke Centre is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1979.
Brantford—Brant is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada from 1904 to 1949 and since 1968.
Mississauga—Lakeshore is a federal electoral district in Peel Region, Ontario, Canada. It has been represented in the House of Commons of Canada since 1979.
London North Centre is a federal electoral district in the city of London in the province of Ontario, Canada, that has been represented in the House of Commons of Canada since 1997.
Oshawa is a federal electoral district in Ontario, Canada, that is represented in the House of Commons of Canada. It currently consists of the City of Oshawa south of Taunton Road. Historically, the riding was dominated by a working-class electorate.
Durham is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada from 1904 to 1968 and since 1988.
Nipissing—Timiskaming is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 2004. The riding was formed by the amalgamation of the former Nipissing riding with the southeastern portion of the former Timiskaming—Cochrane riding. The 2011 electoral results in this riding were challenged in court on the grounds that there were "irregularities, fraud or corrupt or illegal practices that affected the result of the election".
Thornhill is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1997. It covers its namesake Thornhill neighbourhood, which is split between the Cities of Vaughan and Markham. The Vaughan portion also includes parts of the city east of Highway 400 and south of Rutherford Road, including the largely industrial district of Concord and Vaughan's planned downtown; Vaughan Metropolitan Centre. The part in the City of Markham is restricted its portion of Thornhill itself west of Bayview Avenue. The riding was created in 1996 and the east end of the riding was split off into other ridings in 2012.
Waterloo is a federal electoral district in the Waterloo Region of Ontario, Canada, that has been used in the House of Commons of Canada from since 1968. Between 1997 and 2015, the riding was known as Kitchener—Waterloo.
Electoral reform is a change in electoral systems which alters how public desires are expressed in election results.
The federal electoral redistribution of 2012 was a redistribution of electoral districts ("ridings") in Canada following the results of the 2011 Canadian census. As a result of amendments to the Constitution Act, 1867, the number of seats in the House of Commons of Canada increased from 308 to 338. The previous electoral redistribution was in 2003.
Ajax is a federal electoral district in the Durham Region of Ontario.
The 2025 Canadian federal election will take place on or before October 20, 2025, to elect members of the House of Commons to the 45th Canadian Parliament. The date of the vote is determined by the fixed-date provisions of the Canada Elections Act, which requires federal elections to be held on the third Monday in October in the fourth calendar year after the polling day of the previous election, though a current government bill proposes to postpone the date to October 27, 2025, to avoid conflicting with Diwali. In addition to the statutory fixed election date provisions, Canada has a constitutional requirement specified in both section 50 of the Constitution Act, 1867 and section 4 of the Canadian Charter of Rights and Freedoms that elections for the House of Commons must be called no more than five years after the writs for the preceding election are returned.