San Rosendo was first a fort built by the Royal Governor Martín García Óñez de Loyola in 1593.

[4] According to the 2002 census of the National Statistics Institute, San Rosendo spans an area of 92.4 km2 (36 sq mi) and has 3,918 inhabitants (1,930 men and 1,988 women).

[3] As a commune, San Rosendo 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, San Rosendo 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, Mulchén, Negrete, Nacimiento, 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).