The Russian posted a total segment score of 84.92 in Austria as she blew away the rest of the field with a faultless performance, finishing 6.97 points ahead of compatriot Anna Shcherbakova.
It was the familiar Russian trio on the podium with Kostornaia and Shcherbakova joined by Alexandra Trusova, with the 15-year-old posting a season's best score of 74.95 to finish third.
Swiss skater Alexia Paganini finished fourth with a performance that was scored at 68.82 by the judges, while Emmi Peltonen of Finland rounded off the top five on 66.49.
Paganini and Peltonen both improved on their finishes in the 2019 competition, where they finished sixth and eighth respectively. Sportsbeat 2020