[1] As a senior in 2004–05, he earned the Episcopal High School William Caskie Watts MVP Award after helping his squad to a 12–11 record.

[2] In his freshman season at Syracuse, Onuaku was named to the Big East Conference All-Academic Team and earned SU Athletic Director's Honor Roll recognition in each of his first two semesters.

He was, however, named to the Big East Conference All-Academic Team and earned SU Athletic Director's Honor Roll recognition for the second straight year following the fall and spring semesters.

[2][3] In his redshirted sophomore season, Onuaku ranked second in the Big East Conference and ninth in the nation in field-goal percentage with 62.8%.

He was named to the Big East Conference All-Academic Team for the third straight year, and was on the SU Athletic Director's Honor Roll for the fall semester.

On November 2, 2012, Onuaku was selected by the Reno Bighorns in the fourth round of the 2012 NBA Development League draft.

[9] In July 2013, Onuaku joined the Phoenix Suns for the 2013 NBA Summer League[10] and on August 22, 2013, he signed with the New Orleans Pelicans.

[26] On April 7, 2015, Onuaku signed with the Minnesota Timberwolves for the rest of the season to help the team deal with numerous injuries.

Minnesota had to use an NBA hardship exemption in order to sign him as he made their roster stand at 16, one over the allowed limited of 15.

[31] On February 6, 2016, Onuaku signed with the Meralco Bolts of the Philippine Basketball Association as the team's import for the 2016 PBA Commissioner's Cup.

[37] Onuaku signed with the Zhejiang Golden Bulls of the Chinese Basketball Association for the remainder of the 2017–18 season on February 5, 2018, after the team waived Jarnell Stokes.

[38] In March 2018, Onuaku signed again with the Meralco Bolts of the Philippine Basketball Association as their import for the 2018 PBA Commissioner's Cup.