An extremely physical center, who also can play with his back to the basket, and an excellent rebounder at both ends of the court with good orientation in the paint. Last season (2014-15) he was outstanding with the Canton Charge (farm team of the Cleveland Cavaliers) of the NBA Development League, where he contributed 17.5 points and 12.2 rebounds in 41 games. Near the end of the season he was called up by the Minnesota Timberwolves, for whom he played in six games and averaged 4.5 points and 3.5 rebounds per game. Onuaku is a graduate of Syracuse University (2010), where he contributed 9.2 points and 6.0 rebounds per game and set the record for best shooting percentage with 64.8% (540 of 833).
In his first season as a professional (2010-11), he played for the Rio Grande Valley Vipers of the NBA's D-League. The following season he played for Lithuanian Club Neptunas, but was injured. In the 2012-13 season, he signed with the Canton Charge of the D-League, where he began to thrive, being chosen three years in a row for the All Star team of the NBA Development League.