Uasin Gishu is located on a plateau and has a cool and temperate climate. The county borders Trans-Nzoia County to the north, Elgeyo-Marakwet and Baringo counties to the east, Kericho county to the south, Nandi county to the south, south-west and Kakamega county to the west.
The county’s name comes from the Illwuasin-kishu Maasai clan. The land was the grazing area of the clan. They surrendered the land to the colonial government in the Anglo-Maasai agreement of 1911, and were subsequently pushed towards Trans Mara District. The plateau that they once occupied was then registered in its Anglicised version, Uasin Gishu.