He was selected by the Phoenix Fuel Masters in the 2017 PBA draft, but was traded to the TNT KaTropa the same day.

[1] In high school, he played for the EAC-ICA Brigadiers, winning Defensive Player of the Year in the NCAA Season 87 Juniors' division, and earning a spot in the Mythical Team.

[6] In Season 91, the Generals got their first win after five games against the San Sebastian Stags, with Onwubere contributing 13 points and 14 rebounds.

In his final season, Onwubere averaged 18 points, 12.4 rebounds, 2.9 assists, and 1.6 blocks,[17] earning him a spot in the Mythical Five.

[23] On January 20, 2021, Onwubere, along with Clint Doliguez, was traded to the NorthPort Batang Pier for Bradwyn Guinto.

[25] He suffered a high ankle sprain in a game against the Magnolia Hotshots in the Governors' Cup, which put him out initially for the rest of the conference and the season.

[27] As of the end of 2023–24 season[28] Onwubere was also a member of the Team Manila roster for the 2016 FIBA 3x3 All Stars in Doha, Qatar.