Cowansville is a town in south-central Quebec, Canada, located on Lac Davignon 20 kilometres (12 mi) north of the U.S. border.

In recent years, Cowansville has seen its commercial activity blossom mainly due to its proximity to a major freeway, Autoroute 10, and the Eastern Townships ski resort region.

In 1805, Ruiter named the small town as Nelsonville, in honour of British admiral, Lord Horatio Nelson, who was killed in the naval Battle of Trafalgar.

Cowansville saw a strong industrial growth during the 20th century, and became a city on June 25, 1931, and has grown since World War II by various annexations, such as Sweetsburg in 1964.

There is also a hospital, Brome-Missisquoi-Perkins, a municipal court, a federal penitentiary, and a Nature Centre close to Davignon Lake.