Vaudreuil-Dorion is an off-island suburb of Montreal, in southwestern Quebec in the County of Vaudreuil-Soulanges. The result of the merger of two towns, Vaudreuil and Dorion, the city is located on the south shores of the Lake of Two Mountains at the confluence of the Saint Lawrence and Ottawa Rivers, just off the western edge of Île Perrot. The city's population as of 2007 is estimated to be approximately 27,660.

Vaudreuil-Dorion is currently experiencing high population growth as farmland is converted to residential areas and commercial developments. Local bus service is operated by CIT La Presqu'Île connecting to the Dorion-Rigaud commuter rail line.

The city is the point of intersection for two of Canada's busiest highways: Autoroute 40/Autoroute 540/Autoroute 20 (connecting the Quebec City-Windsor Corridor) and the Trans-Canada Highway.