Guyenne ( /ɡwiːˈjɛn/; French: [ɡɥijɛn]; Occitan: Guiana [ˈɡjanɔ]) or Guienne is a vaguely defined historic region of south-western France. The Province of Guyenne, sometimes called the Province of Guyenne and Gascony, was a large province of pre-revolutionary France.

The name Guyenne comes from the Occitan Guiana, which is itself a corruption of the word Aquitaine. However the words Aquitaine and Guyenne came to indicate different entities. The region of Guyenne also became confused with the region of Gascony until this took on a distinct identity in the 17th Century. From this time "Guyenne and Gascony" was a common term corresponding roughly to modern northern Aquitaine.