Boussu (French pronunciation: [busy]; Picard: Boussu-dlé-Mont) is a municipality of Wallonia located in the province of Hainaut, Belgium.

During the late Middle Ages the town gave his name to an important branch of the House of Hénin.

The castle of Boussu was constructed in this period, and important members of this family are buried inside the church.

As its neighbouring municipality, Hornu, Boussu's town is very old and the history of Saint Waudru mentions the existence of a church in the 13th century.

In the acts of the past, Boussu conquered very diverse titles: Buxutum, Bussuth, Bussut, Bossut, Boussut.