[6] He made his NBA debut on December 26, 2016, coming on in the fourth quarter and recording six points and three rebounds in a 131–115 win over the Phoenix Suns.

[10] During his rookie season, Onuaku had multiple assignments with the Rio Grande Valley Vipers, the Rockets' D-League affiliate.

[16] On October 20, 2018, Onuaku was selected with the second overall pick in the 2018 NBA G League draft by the Greensboro Swarm.

[17] On October 3, 2019, Onuaku signed with Wonju DB Promy of the Korean Basketball League to replace Elijah Thomas.

[20] On February 17, 2022, Onuaku won the Israeli Basketball State Cup after Bnei Herzliya Basket edged out Hapoel Tel Aviv 87–82.

[24] On November 13, 2023, Onuaku joined the Goyang Sono Skygunners of the Korean Basketball League (KBL) to replace Jarrod Jones.

[26] On June 27, 2024, Onuaku signed with the Wonju DB Promy of the Korean Basketball League (KBL).