The "arrondissement" of Carcassonne covers the northwestern part of the Aude department; it is surrounded by departments of the Occitanie region and is bordered to the north by the Tarn department, to the northeast by the Hérault department, to the east by the "arrondissement" of Narbonne, to the south by the Pyrénées-Orientales department, to the southwest by the "arrondissement" of Limoux, to the west by the Ariège department and to the northwest by the Haute-Garonne department.