Arzens is located in the urban area of Carcassonne some 11 km west of the city. Access to the commune is by road D119 from Carcassonne passing west through the north of the commune and continuing to Montréal. Access to the town is by road D38 from Sainte-Eulalie in the north to the town, by road D35 from Villesèquelande in the north-east, and by road D211 from Lavalette in the east which continues to join the D119 in the commune. The D43 road from Montreal in the west to Montclar in the south-east passes through the south of the commune. Road D911 goes south from the town to join the D43 in the commune. The A61 autoroute (European route E80) (Autoroute des Deux Mers) passes through the north of the commune but has no exit with the nearest being Exit 22 at Bram in the west or Exit 23 for Carcassonne west to the east. The south of the commune is mostly forest with the rest of the commune farmland and residential area around the town.[3]
Numerous streams rise in the commune and flow north to join the Canal du Midi which passes east–west north of the commune. From west to east there are the Ruisseau de Saint-Pietre, the Ruisseau de la Mialauque, the Ruisseau de Falga, the Ruisseau d'Aribaud, the Ruisseau de Fontasse, and the Ruisseau du Saut which forms much of the eastern border of the commune.[3]