Merbes-le-Château (; ) is a municipality of Wallonia located in the province of Hainaut, Belgium.
On January 1, 2006, Merbes-le-Château had a total population of 4,093. The total area is 30.24 km<sup>2</sup> which gives a population density of 135 inhabitants per km<sup>2</sup>.
The municipality consists of the following districts: Fontaine-Valmont, Labuissière, Merbes-le-Château, and Merbes-Sainte-Marie.