It lies south and west of the Biobío River in the valley of Catirai and is 48 kilometers from Concepción, Chile.

In 1739 Governor José Antonio Manso de Velasco made important adjustments, improving and properly supplying the fortress and constructing between the river and the small Laguna de Rayenantú behind it, deep ditches, that turned the enclosure into an island, and increasing its population to serve as its garrison for the defense of the region and the wooded valleys of the southern mountainous area.

According to the 2002 census of the National Statistics Institute, Santa Juana spans an area of 731.2 km2 (282 sq mi) and has 12,713 inhabitants (6,357 men and 6,356 women).

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

The commune is represented in the Senate by Alejandro Navarro Brain (MAS) and Hosain Sabag Castillo (PDC) as part of the 12th senatorial constituency (Biobío-Cordillera).