Kim Saarinen was born in Hameenlinna, Finland.
Saarinen played for Team HPK U16 in 2021-2022. He went 15-7 with a 3.18 GAA. In 20222-2023, he played for the U18 team and again put up strong numbers, going 10-9 with a 2.96 GAA.
This past season, Saarinen for HPK's junior team and had an outstanding campaign. He finished the season 14-5 with a 2.41 GAA. At the U-18 worlds, he was relegated to the backup job, blanking Norway in his only start and stopping all but one shot in mop-up duty against Team USA.