Oliver Barbosa was born in Pasig City, Manila. He was the 1997 Shell Philippines National Youth Grand Finals Champion. In 2004 he reached the Philippines National semi-finals. The same year he was both the Philippines national under-18 Champion, and the Philippines National Junior Champion. In 2006, he came equal third behind Wesley So and Ronald Dableo at the 2nd Prospero Pichay Cup in Manila. Later that year he was a member of the successful Philippines team that defeated Myanmar in a team contest, his personal contribution being to score 8/12 to assist a clean sweep of all boards. Towards the end of 2010, he competed in the Penang Heritage City Open International Chess Tournament where he came equal first alongside Oliver Dimakiling with 7.5/9. He continued his good form immediately afterwards in the Asean Open Championships 2010 in Singapore, where he again came equal first, this time with Georgian GM Zurab Azmaiparashvili, with a score of 6.5/9, drawing his individual game with the co-leader.

2011 started off with a successful result in the Moscow Open 2011 E, where he came equal second with 7.5/9, half a point behind the winner Vladimir Belous, losing only to Alexander Beliavsky, but defeating his other two GM opponents, namely Pavel Kotsur from Kazakhstan and Russia's Sergey Volkov. In March he came =2nd at the Brunei 2011 IM Tournament 1 behind Dzhurabek Khamrakulov and then came equal first in the Brunei 2011 IM Tournament 2, also played in March. He scored 5/9 - and his first GM norm - at the 10th Asian Individual Championships (2011) in May, and in July he took outright first at the Campomanes Memorial Yangon International Open 2011 in Myanmar, with 7.5/9. Also in July he scored 8/13 to place =2nd with veteran GM Eugenio Torre, half a point behind prodigy GM Wesley So in the National Championships played in Manila, securing his second GM norm. His 3rd GM norm came at the Raja Nazrin Shah Invitational Masters in Kuala Lumpur in September. As his rating is already over 2500, his GM title was ratified by FIDE at its Congress in later October 2011.

2012 has seen him place a splendid 5th with 6/9 at the Asian Continental Chess Championship (2012), qualifying him for participation in the 2013 World Cup and win the Orissa GM Open held in Bhuvaneshwar in India with 8.5/10. He also played on board 2 for the Philippines at the Chess Olympiad (2012) held in Istanbul, scoring 7/10 with a TPR of 2668 and placed =1st at the Bangkok Chess Club Open 2013, scoring 7/9. He also placed 2nd at the 2013 Asian Continental Championship with 6.5/9.

Barbosa was a silver medalist of the 2005 SEA games. In 2003 he coached the Taytay team.