It is located 32 km south of the city of Los Ángeles, close to Chile Highway 5.

According to the 2002 census of the National Statistics Institute, Mulchén spans an area of 1,925.3 km2 (743 sq mi) and has 29,003 inhabitants (14,513 men and 14,490 women).

[3] As a commune, Mulchén is a third-level administrative division of Chile administered by a municipal council, headed by an alcalde who is directly elected every four years.

[1][2] Within the electoral divisions of Chile, Mulchén is represented in the Chamber of Deputies by Juan Lobos (UDI) and José Pérez (PRSD) as part of the 47th electoral district, together with Los Ángeles, Tucapel, Antuco, Quilleco, Santa Bárbara, Quilaco, Negrete, Nacimiento, San Rosendo, Laja and Alto Bío Bío.

The commune is represented in the Senate by Victor Pérez Varela (UDI) and Mariano Ruiz-Esquide Jara (PDC) as part of the 13th senatorial constituency (Biobío-Coast).