奥尔德尼岛（Alderney）是英吉利海峡中的海峡群岛中的一个小岛。属根西行政区管辖。面积7.9平方公里。岛上约有人口2,400人。奥尔德尼岛是海峡群岛中的第三大岛屿。岛上建有机场，与英国本土之间有航班往来。此外同海峡群岛中的其他岛屿和法国有渡轮航线。

Alderney (/ˈɔːldərni/; French:Aurigny [oʁiɲi]; Auregnais: Aoeur'gny) is the most northerly of the Channel Islands. It is part of the Bailiwick of Guernsey, a British Crown dependency. It is 3 miles (5 km) long and 1 ⁄₂ miles (2.4 km) wide. The area is 3 square miles (8 km), making it the third-largest island of the Channel Islands, and the second largest in the Bailiwick. It is around 10 miles (15 km) to the west of La Hague on the Cotentin Peninsula, Normandy, in France, 20 miles (30 km) to the north-east of Guernsey and 60 miles (100 km) from the south coast of Great Britain. It is the closest of the Channel Islands to both France and the United Kingdom. It is separated from Cap de la Hague by the dangerous Alderney Race (French: Raz Blanchard).