Lessines (French: [lɛsin] ⓘ; Picard: Lissene; Walloon: Lissene; Dutch: Lessen [ˈlɛsə(n)] ⓘ) is a city and municipality of Wallonia located in the province of Hainaut, Belgium.

The total area is 72.29 km2 (27.91 sq mi) 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.

The Papignies post office opened on 18 February 1880, Ghoy and Ollignies on 25 May 1905, and Ogy on 5 November 1907.

[4] The Hospital of Our Lady with the Rose, a tentative World Heritage site, and the Castle of l'Estriverie are also in Lessines.