Kitui County shares its borders with seven counties; Tharaka-Nithi and Meru to the north, Embu to the northwest, Machakos and Makueni to the west, Tana River to the east and southeast, and Taita-Taveta to the south.
Kitui county has a total population of 1,136,187 of which 549,003 are males, 587,151 females and33 intersex persons. There are 262,942 household with an average household size of 4.3 persons per household and a population density 37 people per square kilometre.