The Nyanza Province of Kenya (Kiswahili: Mkoa wa Nyanza) was one of 8 Provinces of Kenya before the 2010 constitution did away with provinces and organised the country into 47 counties. Its neighbours were Rift Valley to the north, Nyanza to the south Rift Valley the east and Rift Valley south. The provincial headquarters was Kisumu Town.
There were 6 legally created districts in this province. These were Siaya, Kisumu, Homa Bay, Migori, Kisii, and Nyamira.
After the 2010 constitution, the county boundaries and names followed those of the districts. The province was headed by a provincial commissioner. It is now moribund, but under the office of the president, the region previously known as Nyanza province is now known as Nyanza region and is under a Regional Commissioner appointed by the President.