Kokkonen was a third round pick (84th overall) of the Leafs in the 2019 NHL Entry Draft. Since that time, Kokkonen has played 3 seasons in SM-liiga, competed in two U20 IIHF World Junior Championships in 2020 and 2021 and also had an 11-game trial with the Toronto Marlies last season.
A defensive defenseman, Kokkonen is not going to fill the net, but he can provide some stability on the back end for the Marlies and, perhaps one day, for the Leafs. In 58 games with the Lahti Pelicans this season, Kokkonen has recorded 1 goal and 14 assists for 15 points.