Châtillon-sur-Chalaronne (, literally Châtillon on Chalaronne) is a commune in the Ain department in eastern France.
The town takes its name from a castle built around 1000 AD. It was formerly named Châtillon-les-Dombes.
The Chalaronne flows northwest through the commune and crosses the town. It flows into the Saône from the left, between Saint-Didier-sur-Chalaronne and Thoissey.