District in Provence, now in southeastern France but once in the Holy Roman Empire, lying between the Rivers Rhône (to the west) and Durance (to the south), though not including Avignon, the place of their confluence. Its chief towns were Carpentras and Cavaillon, but its name comes from the hill-top town of Venasques, southeast of Carpentras.
Emma, the heiress of Count Rotbald III of Provence (d.1014), married Count William III of Toulouse, and in her right Toulouse claimed Provence. The County however had been jointly held, and the descendants of Rotbald’s cousins kept their hold on most of the land.
Eventually a settlement was reached in 1125, and part of Provence, including the Comtat Venaissin, was held by the Count of Toulouse with the title of Marquis of Provence. In 1229 Count Raymond VII of Toulouse, as part of the process of rehabilitating himself after the disasters of the Albigensian Crusade, sought to please the Pope by giving him the Comtat.
Provence however was part of the Kingdom of Burgundy, and the Emperor Frederick II, as King, refused to ratify the arrangement, so that the Comtat Venaissin was still part of the lands acquired by Alphonse, Count of Poitou and brother of Louis IX, when his wife, the heiress of Toulouse, succeeded Raymond VII, her father, in 1249.
Countess Joan, who died in 1271 and was childless, sought in her will to leave the Marquisate of Provence to her brother-in-law, Charles of Anjou, King of Sicily and Count of Provence, but King Philip III, as heir to Alphonse, insisted on his rights. He did not however keep the Comtat Venaissin, but in 1274 made good the aborted gift of Raymond VII, so that when the Pope left Rome in 1309 and made his home in Avignon, he was already the lord of the neighbouring land. In 1348 he bought Avignon as well.
The Comtat Venaissin remained Papal territory until the Revolution. It was annexed in 1791 and in 1793 formed a substantial part of the new Department of Vaucluse.