Niagara-on-the-Lake is a town in Ontario, Canada. It is located on the Niagara Peninsula at the point where the Niagara River meets Lake Ontario, across the river from New York, United States. Niagara-on-the-Lake is in the Niagara Region of Ontario and is the only town in Canada that has a lord mayor. It had a population of 19,088 as of the 2021 Canadian census.

The Niagara Peninsula is an area of land lying between the southwestern shore of Lake Ontario and the northeastern shore of Lake Erie, in Ontario, Canada. Technically an isthmus rather than a peninsula, it stretches from the Niagara River in the east to Hamilton, Ontario, in the west. The peninsula is located in the Golden Horseshoe region of Southern Ontario, and has a population of roughly 1,000,000 residents. The region directly across the Niagara River and Lake Erie in New York State is known as the Niagara Frontier.