The municipality consists of 2 major islands (the eponymous Sarangani Island and Balut Island) and 1 minor islet (Olanivan Island), collectively called as the Sarangani Islands, located just south of Mindanao island in the Celebes Sea.
Sarangani is politically subdivided into 12 barangays.
- Mabila (Poblacion)
- Patuco (Sarangani Norte) (includes Olanivan islet)
- Laker (Sarangani Sur)