Belley (French pronunciation: [bəlɛ] ⓘ;[3][4][5] Arpitan: Bèlê) is a subprefecture of the Ain department in the Auvergne-Rhône-Alpes region, France.

In 1385 the town was almost entirely destroyed by an act of arson, but was sequentially rebuilt by the dukes of Savoy, who surrounded it with ramparts of which little is left.

Belley is the home region of St Peter Chanel, the famous 19th-century Marist missionary martyr and protomartyr of Oceania.

Belley features an oceanic climate (Cfb) but with strong continental influences due to its far inland position and its proximity to the Jura mountains under the Köppen system.

The town is famed for its cheese, la Tome de Belley, also known as Chevret or still "Le pavé d'Affinois".