The Chyulu Hills situated 190 km South-East of Nairobi and 30 km South-West of Kibwezi, are of relatively recent volcanic origin and the range is composed of ash cones and craters.
The hills hold no permanent surface water but rainfall percolating through the porus rock feeds many permanent fresh water sources in the surrounding plains, notably Mzima springs and the Tsavo and Galana rivers.
The hills are relatively undisturbed and shelter indigenous vegetation and wildlife. The park comprises the eastern flank of the hills including about half of the forest area. The park boundary runs down the center of the hills along the line of the peaks. The western half is part of the West Chyulu Game Conservation area, owned by several Masai group ranches.