Mathias Tønnessen is a 22-year-old professional football player from NOR. He currently plays for Tromso IL, wearing the number 3 shirt. He plays primarily as a Defender. He stands at 189cm tall and weighs 78kg. His preferred foot is Left. His current market value is estimated at 1000K €.

His most recent move was a Free from KFUM Oslo to Tromso IL on 2026-01-29. The reported fee was 1.1M €.

Throughout the Norwegian Eliteserien 2025, Mathias Tønnessen featured in 29 matches, averaging 2.6 tackles, 1.3 interceptions, and 5.6 clearances per game, while blocking 0.1 shots per game.