The County of Carcassonne (Occitan: Comtat de Carcassona) was a medieval fiefdom controlling the city of Carcassonne, France, and its environs. It was often united with the County of Razès.

The origins of Carcassonne as a county probably go back to the Visigothic period in Septimania, but the first count known by name is Bello of the time of Charlemagne. Bello founded a dynasty, the Bellonids, which would rule many honores in Septimania and Catalonia for the centuries.

Bello was a loyal Carolingian follower and his successor in the county were Carolingian appointees down to about the time of Oliba II, at which point the counties in the outlying regions were beginning to become hereditary possessions in the hands of locally well-endowed families. After Oliba, who ruled both Carcassonne and Razès, his patrimony was ruled jointly by his sons and grandsons. On the death of Acfred II in 933, Carcassonne passed to a woman and, by marriage, to the Counts of Comminges.

The Counts of Comminges continued the practice, extensive in the Midi, of associating brothers, sons, grandsons, and nephews in the government. In 1068, however, Carcassonne was divided among the three daughters of Peter II. In 1069, they sold their comital rights to Raymond Berengar I of Barcelona. The county of Carcassonne was subsumed within Barcelona thereafter, though a viscounty was created in 1082 by Raymond Berengar II.

Counts of Carcassonne

Viscounts of Carcassonne and Razès

In 1069, Garsenda, Ermengarde, and Adelaide sold their comital rights to Carcassonne to Ramon Berenguer I, Count of Barcelona. At some point, Ermengarde married Raymond Bernard of Nîmes, a member of the Trencavel family. Their son, Bernard Ato IV, retook Carcassonne in 1125.