Mulchén is a city and commune in Bío Bío Province of Bío Bío Region, Chile. It was first settled in 1871 by soldiers during the so-called Pacification of the Araucania. In 1875 Mulchén was officially founded.

The city is surrounded by a meander of the Bureo River on all sides except the south, where it is bounded by the Mulchén River. It is located 32 km south of the city of Los Ángeles, close to Chile Highway 5.