The district is situated in a vast floodplain, between the Kilombero River in the south-east and the Udzungwa-Mountains in the north-west.

On the other side of the Kilombero River, in the south-east, the floodplain is part of Ulanga District.

According to the last census in 2002, the population of Kilombero District is 321,611 [2] The main ethnic groups are Wapogoro, Wandamba, Wabena, and Wambunga and several others in small proportions.

[3] The area is predominantly rural with the semi-urban district headquarters Ifakara as major settlement.

In the north-west of the district, Illovo Sugar Company's sugar-cane plantations occupy most of the low lying area.