[2] As a commune, San Fabián is administered by a municipal council, headed by a directly elected alcalde.

), and the council members are:[1] Within the electoral divisions of Chile, San Fabián is represented in the Chamber of Deputies by Marta Bravo Salinas (UDI), Frank Sauerbaum Muñoz (RN), Cristóbal Martínez Ramírez (UDI), Sara Concha Smith (PSC), and Felipe Camaño Cárdenas (DC) for the 2022–2026 term, as a part of the 19th electoral district (together with Bulnes, Cobquecura, Coelemu, Ñiquén, Portezuelo, Quillón, Quirihue, Ninhue, Ránquil, San Carlos, San Nicolás, Treguaco, Chillán, Chillán Viejo, Coihueco, El Carmen, Pemuco, Pinto, San Ignacio, and Yungay).

The commune is represented in the Senate by Loreto Carvajal Ambiado (PPD) and Gustavo Sanhueza Dueñas (UDI) for the 2022–2030 term, as part of the 16th senatorial constituency (Ñuble Region).

According to data from the 2017 Census of Population and Housing, the San Fabián commune had 4,308 inhabitants.

The population density of San Fabian is 2,7/km2 Cities with there respective inhabitants according to the 2002 census.