Mastrov debuted for the California Golden Bears off the bench on February 5, 2021, scoring a career-high 20 points including four made threes in a 51–62 loss to Utah. She was California's highest-ever debutante scorer and the team's top single-game scorer against a Pac-12 opponent at that point in the 2021–21 season.[6] She started the last five games of her freshman season, averaging 7.0 points and 4.3 rebounds per game.[2] She scored 12 points and grabbed 7 rebounds in a 67–55 win over Arizona State on February 21, 2021.[2]
Mastrov played a backup guard role the following three seasons.[7] She scored 9 points in a 102–60 win over McNeese on December 11, 2021, which was California's first 100-point game under head coach Charmin Smith.[2][8] She shot 4-for-7 for a season-high 11 points in an 88–52 win over Florida A&M on December 18, 2022.[9] She scored 10 points and grabbed 5 rebounds in a 61–49 loss to Washington State in the first round of the Pac-12 Conference tournament on March 1, 2023.[2] She scored 14 points shooting 6-for-8 with two threes in a season-opening 89–56 win over CSU Bakersfield on November 6, 2023.[2] She averaged 3.0 points and 1.4 rebounds in 13.7 minutes per game for her career.[2]
Mastrov's father, Mark Mastrov, is the founder of fitness center chain 24 Hour Fitness.[3] Her grandfather, Bert Mastrov, played college basketball as part of the first California team under coach Pete Newell.[4]
Mastrov was one of the NCAA's most-followed women's basketball players on social media, with 1.2 million followers across TikTok and Instagram as of March 2024[update], and one of its highest name, image, and likeness (NIL) earners.[11][7] Her social media posts include lip syncs, basketball photos, swimsuit photos, and NIL brand partnerships.[3][12] She is a close friend of Stanford basketball star Cameron Brink, with whom she played AAU youth basketball.[3] She has been a professional model.[3]