Stepien-Iwumene came up through the ranks with Sutton United before moving to Southampton in 2023 where he went on to play for the Under-18s and Under-21s during his time with the club.
During his time with the Saints, Stepien-Iwumene won the PL2 in the 2022/23 season.
In the summer, the central-midfielder completed a move to Derby County after leaving Southampton after having spent some time on trial with Derby’s Under-21s towards the end of the 2023/24 season, featuring in a handful of matches, before permanently joining the Rams Under-21s.