He currently plays for Lyn Oslo, wearing the number 10 shirt. He plays primarily as a Forward. He stands at 188cm tall and weighs 85kg. His preferred foot is Right. His current market value is estimated at 200K €.

His most recent move was a from FK Arendal to Lyn Oslo on 2024-01-30.

In the Norwegian 1.Divisjon 2025 season, Mathias Johansen scored 5 goals and provided 8 assists across 30 appearances, averaging 0.2 goals per game with 0 shots attempted and 0 on target.