As a youth, Stephan played for Lourdes Celtic and Shelbourne, where he made his senior debut. He signed for United on 01/01/23. He made his debut as a substitute against Sheffield Wednesday and his full debut in the following game at Port Vale.

Negru spent the 2024/25 season at League Two side Salford City, gaining valuable experience with 32 appearances for the Club. Negru is now on loan at fellow League Two side Bristol Rovers.