As a student at St Benedict's College in Bedfordview, Obi represented the in youth competitions. He played for them at the 2006 Under-13 Craven Week competition and for their Under-16 side at the 2009 Grant Khomo Week. He joined Potchefstroom-based side the in 2012 and represented the side in the 2012 Under-19 Provincial Championship competition. He finished as the third-highest try scorer in that competition, scoring ten tries. In 2013, he played Varsity Cup rugby for the, scoring four tries for the side.
Leopards
His first class debut came in the 2013 Currie Cup First Division competition. He missed out on the first game of the season, but started in their second match against the. He started each of the remaining matches of the season, making 14 appearances in total. His first senior try came in their match against the, scoring a dramatic try in injury time that secured a 34–28 victory for the Leopards. He was once again the match-winner against the, with the second of his two tries coming with four minutes left to beat the Cavaliers 22–17. He scored another brace in their match against the to end the season with a tally of eight tries, joint-sixth in the competition. He was subsequently included in the wider training group prior to the 2014 Super Rugby season.
In February 2015, Obi – along with fellow winger Sylvian Mahuza – started training with Port Elizabeth-based side the, following a dispute about the validity of their contracts with the. An agreement was reached and Obi officially joined the Kings on 27 February.
After just one season at the Kings, Obi joined the Pretoria-based side for the 2016 Super Rugby season.
Cheetahs
He was on the move again in 2017, securing an early release from his Bulls contract to join the on a two-year deal.
Representative rugby
In 2013, he was included in the South Africa Under-20 side that competed at the 2013 IRB Junior World Championship. He scored four tries in his five appearances and finished joint-second in the try-scoring charts behind compatriot Seabelo Senatla, helping the S.A. Under-20 side to third place in the competition.
