Nigeria
In his country he played for Kaduna United Football Club, Enyimba International F.C. and Kano Pillars Football Club. Kilmarnock
On 2 April 2013, Gabriel joined Scottish Premier League side Kilmarnock as a free agent, signing a three-year contract. On 29 November 2013 he made his debut for his new team, in a Scottish Cup tie against Dundee United where he conceded a penalty in a 2–5 away defeat. In November 2013, Reuben demanded to leave Kilmarnock in the January 2014 window.
In January he was released, after the club accepted his request.
Waasland-Beveren
In January 2014, Reuben went on trial with Tottenham Hotspur in the Premier League. However, nothing came of it, and he joined Belgian Pro League club Waasland-Beveren on a one 1/2-year contract late in the month.
Reuben was also selected to the 2014 World Cup by coach Stephen Keshi. He made his debut in the tournament on 30 June, replacing injured Ogenyi Onazi in the 59th minute of an eventual 0–2 loss against France for the round-of-16.