The 22-year old triple gold medalist from Zagreb, who missed the whole of last season due to illness and injury, finished in a combined time of one minute 43.7 seconds -- more than a second ahead of last season's overall, giant and slalom champion Anja Paerson of Sweden.
This was Kostelic's 20th World Cup win and her first since March 2003. She had several operations on her right knee as well as surgery to remove her thyroid last January.
Finland's Tanja Poutiainen was third on Saturday.
Poutiainen won Friday's giant slalom in Aspen, Paerson was second and Kostelic third.