Kisumu County is one of 47 counties in the Republic of Kenya. Its borders follow those of the original Kisumu District, one of the former administrative districts of the former Nyanza Province in western Kenya. Its headquarters is Kisumu City which is the third largest city in Kenya after the capital Nairobi and the coastal city of Mombasa. It has a population of 1,155,574 (according to the 2019 National Census). The land area of Kisumu County totals 2085.9 km2.
Kisumu County's neighbours are Siaya County to the West, Vihiga County to the North, Nandi County to the North East and Kericho County to the East. Its neighbour to the South is Nyamira County and Homa Bay County is to the South West. The county has a shoreline on Lake Victoria, occupying northern, western and a part of the southern shores of the Winam Gulf.