Onuora went on to feature heavily for The Gills for the next two seasons before Neil Warnock tempted the player into moving to Bramall Lane to sign a two-year deal with Sheffield United, reuniting Onuora with his former Gillingham strike partner Carl Asaba. However football for Onoura was rare with the club and after starting the season alongside Asaba, he only made 8 appearances in both league and cup competitions, scoring one goal against Burnley. But after a season-ending Achilles injury, he never played for United again. In August 2003, it was announced that he would be carrying on with The Blades, but was loan listed where he signed for Wycombe Wanderers at the start of the season on a one-month loan deal.