Fontenille-Saint-Martin-d'Entraigues is a commune in the Deux-Sèvres department in the Nouvelle-Aquitaine region in western France. It was created in 1973 by the merger of two former communes: Fontenille and Saint-Martin-d'Entraigues.
The main hamlets in the commune are located on the banks of the river Boutonne, which flows southwestward through the commune.