Kostiukovich began learning to skate in 2009. She trained as a single skater until 2016. Kostiukovich and Dmitrii Ialin began competing together in 2016. They were coached by Vasili Velikov in Saint Petersburg.
Kostiukovich/Ialin started their season by competing in the 2018 Junior Grand Prix series. At their first Junior Grand Prix event of the season they won the gold medal in Linz, Austria. They were ranked first in both the short program and the free skate and won the gold medal by a margin of more than 14 points over the silver medalist, their teammates Anastasia Poluianova / Dmitry Sopot. At their second JGP event of the season they won the silver medal in Ostrava, Czech Republic. They were ranked first in the short program and second in the free skate, and were beaten by the gold medalists, their teammates and training partners Kseniia Akhanteva / Valerii Kolesov by a margin of about 4 points. At this event they set the junior-level pairs' record for the short program. With these results they qualified for the 2018–19 Junior Grand Prix Final. At the JGP Final, Kostiukovich/Ialin won the silver medal after placing first in the short program and second in the free skate. They were part of a Russian sweep of the pairs' podium. Kostiukovich/Ialin beat the bronze medalists, Apollinariia Panfilova / Dmitry Rylov, by about 3 points but the race for the gold medal were really tight. The gold medalists, their training partners Mishina/Galliamov, beat Kostiukovich/Ialin by a margin of only 1.1 point. At this event Kostiukovich/Ialin scored their personal best score of 189.53 points and they also upgraded their junior-level pairs' record for the short program. At the 2019 Russian Championships, Kostiukovich/Ialin placed eighth in the senior event and second in the junior event, and were assigned to the 2019 World Junior Championships alongside Mishina/Galliamov and Panfilova/Rylov. They won the short program at Junior Worlds, narrowly ahead of both of the other Russian teams, and were awarded a gold small medal for the result. In the free skate, they had underrotations called on their combination jump and Kostiukovich fell on a throw triple Salchow. As a result, they finished third in the free skate and third overall. Ialin admitted "unfortunately, not everything worked out today." Kostiukovich expressed the hope that "at our next Junior World Championships we can improve, fix our mistakes, and gain experience to be able to win."
2019–2020 season: Struggles and end of partnership with Ialin
Kostiukovich/Ialin were initially assigned to the 2019 ISU JGP Croatia Cup in Zagreb, Croatia. However, they withdrew from the event due to puberty-related struggles faced by Kostiukovich. The team continued to compete domestically, qualifying for both the senior and junior-level Russian championships through the Russian Cup series. Kostiukovich/Ialin placed eighth at 2020 Russian Championships in January, and later placed fifth at the junior championships in February, missing the podium for the first time in two seasons. On 13 March 2020, the pair announced the amicable end to their partnership. On 18 July 2020, Kostiukovich announced on Instagram that she'd teamed up with Aleksei Briukhanov.
Programs
With Ialin
Records and achievements
Set the junior-level pairs' record of the new +5 / -5 GOE system for the short program at the 2018 JGP Czech Republic.
Upgraded their junior-level pairs' record for the short program at the 2018–19 JGP Final.
Upgraded their junior-level pairs' record for the short program at the 2019 World Junior Championships. This record was later broken by Apollinariia Panfilova / Dmitry Rylov at the 2019 JGP Poland.
