布列塔尼半岛（法语：Bretagne，[bʁətaɲ]；布列塔尼语：Breizh，[brɛjs]；加洛语：Bertaèyn）是法国西北部历史上的一个半岛，文化及行政上的一个地区名称。布列塔尼半岛的北部面向英伦海峡，南部对着比斯开湾，古城阿摩里卡，范围包括塞纳河和罗亚尔河之间的沿海地区。整个半岛的面积有34,023 km²。

凯尔特人是布列塔尼半岛最早的居民，而布列塔尼亦是昔日的六个凯尔特邦国之一。后来布列塔尼半岛被凯撒征服，成为罗马的鲁格顿西斯行省。5世纪时，不列颠人入侵，所以这块西北端地区被称作布列塔尼，外号小不列颠（与大不列颠相对）。

Brittany (/ˈbrɪtənɪ/; French:Bretagne [bʁə.taɲ]; Breton:Breizh, pronounced [bʁɛjs] or [bʁɛχ]; Gallo: Bertaèyn, pronounced [bəʁ.taɛɲ]) is a cultural region in the north-west of France. Covering the western part of Armorica, as it was known during the period of Roman occupation, Brittany subsequently became an independent kingdom and then a duchy before being united with the Kingdom of France in 1532 as a province governed as if it were a separate nation under the crown. Brittany has also been referred to as Less, Lesser or Little Britain (as opposed to Great Britain). It is bordered by the English Channel to the north, the Celtic Sea and the Atlantic Ocean to the west, and the Bay of Biscay to the south. Its land area is 34,023 km² (13,136 sq mi).