The Nigeria international has failed to get on the scoresheet since he rejoined the side in December despite featuring in 11 games for the side last season.
However, against Michael Reschke’s men, the long-awaited goal came and proved decisive for his side as they start the 2018-19 season on a winning note.
In the 76th minute, the Nigeria international broke the deadlock - shortly after replacing Jean Philippe Mateta.
DR Congo international Chadrac Akolo was introduced in the 81st minute as Stuttgart desperately searched for an equalizer.
Ujah will be hoping to get a starting role when Mainz 05 lock horns with Nürnberg in their next league game at the Max-Morlock-Stadion on September 1.