Waterloo is a municipality in Wallonia, located in the province of Walloon Brabant, Belgium, which in 2011 had a population of 29,706 and an area of 21.03 km2 (8.12 sq mi). Waterloo lies a short distance south of Brussels, and immediately north-east of the larger town of Braine-l'Alleud. It is the site of the Battle of Waterloo, where the resurgent Napoleon was defeated for the final time in 1815. Waterloo lies immediately south of the official language border between Flanders and Wallonia.

Walloon Brabant is a province located in Belgium's French-speaking region of Wallonia. It borders on the province of Flemish Brabant and the provinces of Liège, Namur and Hainaut. Walloon Brabant's capital and largest city is Wavre.