The river Boulogne (French: [bulɔɲ]) is located in western France in the départements Loire-Atlantique and Vendée.

It is 86.5 km (53.7 mi) in length and flows north from the source near Saint-Martin-des-Noyers, through Les Essarts and La Merlatière, then through Boulogne, Vendée and Les Lucs-sur-Boulogne into the Lac de Grand-Lieu. This lake is drained by the river Acheneau towards the Loire.