Saint-Ouen-des-Alleux (; ) is a commune in the Ille-et-Vilaine department in Brittany in northwestern France.
Saint-Ouen-des-Alleux is located northeast of Rennes and south of Mont Saint-Michel.
The adjacent communes are Saint-Christophe-de-Valains, Le Tiercent, Saint-Hilaire-des-Landes, Saint-Marc-sur-Couesnon, Mézières-sur-Couesnon, and Vieux-Vy-sur-Couesnon.
Inhabitants of Saint-Ouen-des-Alleux are called audonniens in French.
Saint-Ouen-des-Alleux is twinned with: