For hire, the skater received 89.86 points, which exceeds her world record.
Anna Shcherbakova took second place - 79.93, Alexander Trusov became the third with a score of 76.46.
Elizaveta Tuktamysheva (75.74) and Evgeny Medvedev (71.08) became the fourth and fifth, respectively.
Girls will show their free program on December 28.
Earlier, Kostornaya stated that she had never pursued referee ratings.