Keiyo South is an electoral constituency in Kenya.
It is one of four constituencies of Elgeyo-Marakwet County.
The constituency has 6 wards, all of which elect a Member of County Assembly (MCA) for Elgeyo Marakwet County which sits in the county Headquarters, Iten.
The wards are namely: Metkei, Kabiemit, Chepkorio, Soy South and Soy North.
The constituency was established for the 1969 elections, one of two constituencies of the former Keiyo District.