On January 1, 2006, Braine-le-Château had a total population of 9,446. The total area is 22.70 km² which gives a population density of 416 inhabitants per km².
The municipality consists of the following districts: Braine-le-Château and Wauthier-Braine, which were municipalities of their own until 1977.
Braine-le-Château is a medieval village in which remain many buildings from the Middle Ages. Among them are the pillory (1521), the village mill (c. 1200) and the Maison du Bailli (c. 1535).