[1] Mrázková/Mrázek made their competitive debut internationally at the Egna Dance Trophy at the end of the 2020–21 season, finishing in ninth place.

As a result, they were not assigned to compete at the 2022 World Junior Championships but went on to win the gold medal at the Egna Trophy in their second appearance there.

The siblings maintained their lead in the free to take the title by a nearly 15-point margin over silver medalists Lim/Quan of South Korea.

The siblings also said they were nervous in the face of the best possible junior competition, some of whom, such as the eventual gold medalist Canadian team Bashynska/Beaumont, they had never met before.

He said they were "incredibly happy" at the outcome after the problems in Torino, also indicating that they planned to compete at the senior level the following season.

[10][11] For their senior debut free dance, the duo selected Tchaikovsky's Swan Lake, which Mrázek called "a big challenge for us," explaining "our goal is for the audience to feel like they are in the National Theatre.

[16] They went on to make their European Championship debut at the 2024 edition in Kaunas, where they finished ninth in the rhythm dance.

[18] Mrázková/Mrázek were eleventh in the free dance with another improved personal best, but remained thirteenth overall, while their fellow Czechs moved up to fifteenth.

[19] Mrázková and Mrázek began the season by competing at the 2024 Denis Ten Memorial Challenge, where they finished fourth.