Authe is located some 45 km east by south-east ofRethel and 20 km north-east ofVouziers. Access to the commune is by road D12 fromBrieulles-sur-Bar in the north which passes through the centre of the commune and the village and continues south to join the D947 south of the commune. The commune consists entirely of farmland.[3]
TheBar river forms the south-western border of the commune as it flows north-west to follow theCanal des Ardennes to join theMeuse nearVrigne-Meuse. TheRuisseau de Saint-Pierremont flows from the north-east of the commune past the village and joins the Bar on the south-western border of the commune.[3]