She earned the bronze medals in the junior women's events at the 2018 Volvo Open Cup and 2018 Tallinn Trophy before placing fourth at the 2019 Estonian Championships.

She defended her junior title at the 2019 Tallinn Trophy and placed second at the 2019 Ice Star in the lead up to the 2020 Estonian Championships, where she won the silver medal behind Eva-Lotta Kiibus.

[3] She revealed in 2023 that she had been suffering from an uncertain illness for some time prior the 2020 World Junior Championships, and following her poor showing there she was diagnosed with "severe" aplastic anemia.

Petrõkina required a bone marrow transplant, but could not find a suitable donor, and was hospitalized for five months while undergoing immunosuppression therapy.

Initially advised that she would not be able to return to skating for two to three years, a prospect she considered tantamount to the end of her career and which caused "a little depression," she was ultimately able to resume training in advance of the following season.

She placed seventh at the event and followed that performance up with a fourth-place finish at the 2021 JGP Austria, a career-best placement for her on the Junior Grand Prix circuit.

[2] In November, Petrõkina made her senior international debut at her first Challenger series event, the 2021 CS Cup of Austria, where she won the bronze medal behind Japanese skater Wakaba Higuchi, and South Korea's Park Yeon-jeong.

She received a second Challenger assignment the following weekend, the 2021 CS Warsaw Cup, where she won the silver medal behind Russian competitor Maiia Khromykh and ahead of Ekaterina Kurakova of Poland.

[2] Due to Petrõkina's national results, she qualified as the top-seeded Estonian woman to one of two berths for her country at the 2022 European Championships in Tallinn.

She finished eighth, also defeating Kiibus for a third time that season, but despite this, she was not named to the Estonian Olympic team due to the national federation's criteria for assigning the spot.

[2] She went on to place ninth at the 2023 World Championships in Saitama, achieving her "minimum goal" of a top ten ordinal that would secure a second Estonian women's berth the following year.

[2] She began the Grand Prix at the 2023 Skate America, where she finished fourth in the short program, 5.05 points back of third-place Isabeau Levito and 0.78 ahead of Mone Chiba in fifth.

[17] Assigned to compete at the 2023 CS Golden Spin of Zagreb, Petrõkina broke her left fibula falling out of a jump in practice, and withdrew from the event.

"[23] She remained in Canada for a time after the championships to work with choreographer, Mark Pillay, saying she planned to focus on full recovery before preparations for the next season.

[24] Petrõkina began the season by competing on the 2024–25 ISU Challenger Series, finishing seventh at the 2024 Lombardia Trophy and winning silver at the 2024 Trophée Métropole Nice Côte d'Azur.

Going on to compete on the 2024–25 Grand Prix series, she hada rough outing at the 2024 NHK Trophy, where she finished a disappointing tenth place.

She skated a strong short program, where she landed a triple Lutz-triple toe loop combination, and she finished that segment in second place.