Mychajlo Kochan gained his first international experience in 2017 when he won the gold medal at the U18 World Championships in Nairobi with a width of 82.31 m with a 5 kg hammer. Then he also won the European Youth Olympic Festival (EYOF) in Győr with a throw on 78.28 m. The following year he took part in the U18 European Championships there, where he set a new world record in the U18 age group with 87.82 m. Only a few days later he reached the U20 World Championships in Tampere and won the silver medal with the 6 kg hammer with 79.68 m. In autumn he started at the Youth Olympic Games in Buenos Aires and won the gold medal. In 2019 he also won the U20 European Championships in Borås, Sweden, with 84.73 m, with which he not only set a championship record but also a new U20 European record. Only the Qatar Ashraf Amgad el-Seify threw in this age group. In addition to his successes in the youth field, he also qualified for the first time for the World Championships in Doha , where he immediately reached the finals and finished fifth there with a new best of 77.39 m.
In 2019 Kochan became Ukrainian hammer throw champion.