The town has its roots in the Mapuche and Spanish races, as produced with the arrival of Franciscan missionaries in the 18th century.

According to the 2002 census of the National Statistics Institute, Quilaco spans an area of 1,123.7 km2 (434 sq mi) and has 4,021 inhabitants (2,110 men and 1,911 women).

[3] As a commune, Quilaco 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, Quilaco 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, Mulchén, 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).