Boussu-en-Fagne (French pronunciation: [busy ɑ̃ faɲ]; Walloon: Boussu-el-Fagne) is a village of Wallonia and a district of the municipality of Couvin, located in the province of Namur, Belgium.

From the early Middle Ages, the territory gradually became part of the lands of the lords of Chimay.

A castle, château de Boussu-en-Fagne, was built here, burnt down by Spanish troops before 1565 and successively rebuilt.

Its current appearance is in a Gothic Revival style.

In addition, there is a smaller manor house further along the road to Frasnes-lez-Couvin [fr], called the manoir de la Motte.