Wellens signed his first professional contract with Manchester United in May 2020. He made his debut for the u21 side in the EFL Trophymatch against Rochdale in the 2020–21 season, and starting all 3 group games in the 2021-22 season. In September 2022, Wellens joined Oldham Athleticon loan, making 6 league appearances and scoring one goal, leaving in January 2023.
Reading
On 1 September2023, Wellens joined League One side Reading on an initial one-year contract with their U21 side, extending for a further year. Wellens left the club in May 2025 having only made 3 appearances in the EFL Trophy.