Cangas de Onís is a municipality in the eastern part of the province and autonomous community of Asturias in the northwest of Spain. The capital of the municipality is also Cangas de Onís.

More than seventy square kilometres of the conceyu form part of the Parque nacional de los Picos de Europa.

Within the park is the village of Covadonga, where the battle of Covadonga (about 722), the first major victory by a Christian military force in Iberia after the Islamic conquest, marks the starting-point of the Reconquista. Cangas de Onís is the site of the first church constructed in post-conquest Iberia, Santa Cruz de Cangas de Onís (737), built on an ancient dolmen.

A parish named Cangas de Onís is attested for the 14th century. The stone bridge across the Sella River was built in the 14th or 15th century.

Cangas de Onís was represented in the Junta General of the principality of Asturias in 1504. Covadonga began to be developed as a pilgrimage site in the 16th century, attracting commerce. The settlement of Cangas de Onís grew rapidly in the mid 19th century. A meteorite fall is recorded for the year 1866.

Cangas de Onís/Cangues d'Onís was bombarded several times in the Spanish Civil War. It served as the seat of the Regional Council in the "pre-autonomous regime" of 1978-1981 prior to the entering into force of the Statute of Autonomy of the Principality of Asturias on 31 January 1982.