Orillia (/əˈrɪliə/) is a city in Ontario, Canada, about 30 km (18 mi) north-east of Barrie in Simcoe County. It is located at the confluence of Lake Couchiching and Lake Simcoe. Although it is geographically located within Simcoe County, the city is a single-tier municipality. It is part of the Huronia region of Central Ontario. The population in 2021 was 33,411.
It was incorporated as a village in 1867, but the history of what is today the City of Orillia dates back at least several thousand years. Archaeologists have uncovered evidence of fishing by the Huron and Iroquois peoples in the area over 4,000 years ago, and of sites used by Aboriginal peoples for hundreds of years for trading, hunting, and fishing.