The town's population is 81,302 (2019 census), and it is still growing due to its proximity to the Kenyan capital city of Nairobi.

Athi River, also known as Mavoko, was carved off the Nairobi County Council in 1963, when the latter was disbanded.

Mavoko municipality has six wards (Athi River West, Katani, Kinanie/Mathani, Makadara, Muthwani and Sophia).

Some of the factors influencing the rapid growth of businesses in the area include the increased real estate development in the region and the proximity to Nairobi City and mining companies.

Athi River is also linked to Nairobi via the Nairobi-Mombasa Highway (commonly known as Mombasa Road), a tarmacked dual carriageway, and to nearby Kitengela by Namanga Road, a tarmacked single carriageway.