Early career Vasilj started playing football at a local club, before joining the youth academy of his hometown team
Zrinjski Mostar in 2010. He made his professional debut against
Željezničar on 10 April 2013 at the age of 17. In July 2014, he was sent on a season-long loan to
Igman Konjic. In July 2015, he was loaned to
Branitelj until the end of the season. In July 2017, Vasilj signed with German side
1. FC Nürnberg. In July 2019, he joined Ukrainian outfit
Zorya Luhansk.
FC St. Pauli In May 2021, Vasilj moved to
FC St. Pauli on a three-year deal. He made his official debut for the team on 25 July against
Holstein Kiel and kept a clean sheet. In January 2024, he signed a new long-term contract with the squad. Vasilj was an important piece in FC St. Pauli's conquest of the
2. Bundesliga title, his first trophy with the club, which was sealed on 19 May and earned them promotion to the
Bundesliga. He played his 100th game for the side against
FC Augsburg on 15 September. ==International career==