Athi River is a town outside Nairobi, Kenya in Machakos County. The town is named after the Athi River, which passes through. It is also known as Mavoko. Athi River hosts the Mavoko Municipal Council and is the headquarters of Mavoko division, which is part of Machakos County. The town's population is 81,302, and it is still growing due to its proximity to the Kenyan capital city of Nairobi.