[5] Thomson made his NHL debut on November 12, 2021, with the Senators in a 2–0 loss to the Los Angeles Kings after being recalled the same day from Belleville due to a breakout of COVID-19 in the team.
[11] He was immediately slotted into the roster alongside Nick Holden in the November 24 game versus the Vegas Golden Knights, giving up a goal in the third period.
[15] On October 1, 2023, after being put on waivers by the Senators, Thomson was claimed by the Anaheim Ducks.
[19] He helped Belleville make it to the second round of the Calder Cup playoffs for the first time in team history, but was surpassed by other prospects.
This biographical article relating to a Finnish ice hockey defenceman is a stub.