The Varenne () is a long river in western France located in the departments of Orne (Normandy) and Mayenne (Pays de la Loire). It is a tributary of the river Mayenne on the right side, and so is a sub-tributary of the Loire by Mayenne and Maine. It flows into the Mayenne near Ambrières-les-Vallées. Its longest tributaries are the ÃÂgrenne, the , the Halouze and the Andainette. The largest town on the Varenne is Domfront en Poiraie.