Kiambu County is a county in the former Central Province of Kenya. Its capital is Kiambu and its largest town is Thika town. Kiambu County is the second most populous county in Kenya after Nairobi County. Kiambu County borders Nairobi and Kajiado Counties to the South, Machakos to the East, Murang'a to the North and North East, Nyandarua to the No…Kiambu County is a county in the former Central Province of Kenya. Its capital is Kiambu and its largest town is Thika town. Kiambu County is the second most populous county in Kenya after Nairobi County. Kiambu County borders Nairobi and Kajiado Counties to the South, Machakos to the East, Murang'a to the North and North East, Nyandarua to the North West, and Nakuru to the West. It has a population of 2,417,735.