Wallin started his career in Essviks AIF, and played for the academy team of
GIF Sundsvall. When he was not given a chance for their senior team, he joined
Hudiksvalls FF in the third tier. Hudiksvall were relegated, but Wallin was signed by
Degerfors IF, bypassing the second tier to sign for the Allsvenskan club. Wallin made his
Allsvenskan debut on 2 April 2023 against Hammarby.
Peterborough United On 1 August 2024, Wallin signed for
EFL League One side
Peterborough United for an undisclosed fee on a two year deal with an option for a third. On 2 October 2025, Wallin left Peterborough by mutual consent, wanting to return to Sweden to continue his education. On 15 December 2025, Wallin announced his retirement. ==Career statistics==