Kai Karsten (born 22 June 1968) is a retired German sprinter who specialized in the 400 metres.
Karsten competed for the club Eintracht Braunschweig, which in athletics enters a joint team with other Braunschweig-based clubs under the name of LG Braunschweig.
In 1994, he won the national championship in the 400 metres.Karsten represented Germany in the 4 × 400 metres relay events at the 1994 European Athletics Championships in Helsinki, the 1995 World Championships in Athletics in Gothenburg, and the 1996 Summer Olympics in Atlanta.