[6] In July 2018, Gerasimenko won the gold medal in the 50 metre breaststroke with a time of 28.03 seconds at the 2018 European Junior Swimming Championships in Helsinki, Finland.

[10] A few months later, in October 2018 at the 2018 Summer Youth Olympics in Buenos Aires, Argentina, Gerasimenko won his first gold medal of the competition on the first day in the 4×100 metre mixed freestyle relay, finals relay time of 3:28.50, for his contributions in the prelims heats and placed seventh in the final of the 100 metre breaststroke the following day with a time of 1:02.43.

[11] For the 50 metre breaststroke at the 2019 European Junior Swimming Championships, held at the Palace of Water Sports in Kazan in July, Gerasimenko won the gold medal with a time of 27.89 seconds.

[28] Following the Swimming World Cup, Gerasimenko competed at his first senior international championships, the 2021 European Short Course Swimming Championships in Kazan in November, where he placed 16th in the prelims heats of the 50 metre breaststroke and did not advance to the semifinals as he was the fourth-fastest Russian swimmer in the prelims heats with his time of 26.80 seconds and only the fastest two were eligible to advance.

[29] Gerasimenko was declared not welcome at European swimming competitions organized by LEN as part of a ban applied to all Russian and Belarusian nationals starting 3 March 2022, effective immediately, and continuing indefinitely.

[33] On the first morning of the 2023 Russian National Championships, in April at the Palace of Water Sports in Kazan, Gerasimenko ranked sixth in the preliminaries of the 100 metre breaststroke with a time of 1:01.28 and qualified for the evening semifinals.

[37] In the morning preliminaries of the 50 metre breaststroke on day five, Gerasimenko ranked eleventh with a time of 27.78 seconds and advanced to the evening semifinals.