Hachenburg is a town in the Westerwaldkreis in Rhineland-Palatinate, Germany.
The town lies in the Westerwald between Koblenz and Siegen, roughly 10km west of Bad Marienberg on the river Nister. Hachenburg is the administrative seat of the Verbandsgemeinde of Hachenburg, a kind of collective municipality (See Verbandsgemeinde).