Lessines (French pronunciation: [lɛsin] (listen); Dutch: Lessen, Dutch pronunciation: [ˈlɛsə(n)] (listen); Picard: Lissene, Walloon: Lissene) is a city and municipality of Wallonia located in the province of Hainaut, Belgium. As of the 2014 census, The municipality's total population was 18,637. The total area is 72.29 km² (27.91 square miles) which gives a population density of 247 inhabitants per km².

The municipality consists of the following districts: Bois-de-Lessines, Deux-Acren, Ghoy, Lessines, Ogy, Ollignies, Papignies, and Wannebecq.

Lessines is a municipality of Picardy Wallonia. It is primarily known as the birthplace of the Surrealist painter René Magritte (1898 – 1967).