Smiths Falls is a town in Eastern Ontario, Canada, 72 kilometres (45 mi) southwest of Ottawa. As of the 2021 census it has a population of 9,254. It is in the Census division for Lanark County, but is separated from the county. The Rideau Canal waterway passes through the town, with four separate locks in three locations and a combined lift of over 15 metres (49.2 ft).

Eastern Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario which lies in a wedge-shaped area between the Ottawa River and St. Lawrence River. It shares water boundaries with Quebec to the north and New York State to the east and south, as well as a small land boundary with the Vaudreuil-Soulanges region of Quebec to the east.