on august 2, 2018, kovalenko was signed to an improved three-year contract to continue his development and remain within lokomotiv yaroslavl. in the 2018–19 season, kovalenko scored his first professional goal in an opening night 5–0 victory over sibir novosibirsk on september 4, 2018. playing in an reduced role due to his youth, kovalenko still contributed offensively, scoring 2 goals, including the game-winner, in a 4–3 victory over hc vityaz on september 20, 2018. he was later named as the khl's best rookie of the week for a second occasion.