[2][3] Onuoha revealed "he had a strict Nigerian upbringing and that school came first and if he did not study properly and successfully, he was forbidden by his mother and father from playing football or athletics".

[21] Though Onuoha's natural position is centre-half, manager Kevin Keegan initially played him at right back with the intention of improving his passing ability.

[53] It wasn't until on 20 October 2008 when he made his return from injury, coming on as a substitute for Micah Richards in the 58th minute, in a 2–2 draw against Newcastle United.

[55] But after City's 3–0 defeat to Nottingham Forest in the FA Cup, he started every single game until the end of the season, forming an effective partnership with Richard Dunne in the centre of defence.

[65] Onuoha didn't make return to the first team until on 24 January 2010 against Scunthorpe United in the fourth round of the FA Cup, as they won 4–2.

[69] After returning from a loan spell at Sunderland, Onuoha was linked with a move away from Manchester City, as various Premier League clubs made bids for him ahead of the 2011–12 season.

[72] However, his first team opportunities at Manchester City were limited as Manager Mancini said: Onuoha will stay with us because he is homegrown but he knows it is difficult for him to play often.

[89] On 26 January 2012, Onuoha agreed to a four-and-a-half-year deal with Premier League side Queens Park Rangers, reuniting him with his former manager Mark Hughes.

[90] Onuoha made his Queens Park Rangers debut, playing the whole game, in a 2–2 draw against Aston Villa on 2 February 2012.

[92] However, Queens Park Rangers found themselves in the relegation zone and he had to help in the fight to retain their Premier League status for the next season.

[93] Amid the relegation battle, Onuoha set up a goal for Djibril Cissé to score a late consolation, as Queens Park Rangers lost 6–1 to local rivals, Chelsea on 29 April 2012.

[99] He then helped the side earn four clean sheets throughout January against Chelsea, Tottenham Hotspur, West Bromwich Albion and Manchester City.

[114] He was a member of the Queens Park Rangers side which won the 2014 Championship play-off final 1–0 against Derby County on 24 May 2014 at Wembley Stadium.

[116] At the start of the 2014–15 season, however, Onuoha found himself out of the first team and placed on the substitute bench due to new signings made over the summer.

[121] It wasn't until on 22 November 2014 when Onuoha made his return to the first team from injury, starting the whole game, in a 1–0 loss against Newcastle United.

[123][117] During a 2–1 loss against Arsenal on 26 December 2014, Onuoha was head-butted by opposition player, Olivier Giroud, which resulted in his sending off in the 53rd minute; despite this, he continued playing for the rest of the match.

[129] Amid the transfer speculation, Onuoha was appointed club captain, succeeding Joey Barton, who had left over the summer.

[140] At the end of the 2015–16 season, Onuoha was ever-present in Queens Park Rangers matches, as he went on to make 48 appearances and scoring two times in all competitions.

[149] This led some Queens Park Rangers' supporters to call for Onuoha to be dropped from the first team against Rotherham United on 18 March 2017, but he proved them wrong when he scored the third goal of the season in a 5–1 win.

[152] Despite this, both Onuoha and Grant Hall were praised by new signing Joel Lynch for their improvement in defence throughout the 2016–17 season, as well as, "pushing each other on to greater heights in order to stay in the team.

[160] It wasn't until on 9 December 2017 that Onuoha made his return from injury, playing the whole game in a 3–1 loss against Leeds United.

[162] During a 4–0 loss against Hull City on 7 April 2018, Onuoha was sent–off in the last minute of the game for a professional foul on Markus Henriksen; and served a three match suspension.

[163] Despite being absent that saw him miss seventeen matches during the 2017–18 season, Onuoha helped the side finish sixteen place in the league.

"[168] Onuoha made his Real Salt Lake debut, coming on as a late substitute, in a 1–1 draw against Sporting Kansas City on 30 September 2018.

[170] Having been initially placed on the substitute, Onuoha was featured in the three matches in the MLS Cup Playoffs, as they lost Sporting Kansas City 5–3 on aggregate.

[175] It wasn't until on 10 August 2019 when Onuoha made his return from injury, coming on as a substitute in the 76th minute, in a 2–1 win over Sporting Kansas City.

[177] Onuoha helped the side qualify for the MLS Cup Playoffs but lost 2–0 against Seattle Sounders FC on 24 October 2019.

[181] He was invited by Nigeria manager Berti Vogts to represent Nigeria at the 2008 Africa Cup of Nations; however, Onuoha turned down the opportunity because his club, Manchester City, had recently had a change of manager and he did not want to lose his place in the team by being absent on international duty for a month.

[185] During the Championships, Onuoha was subjected to racist abuse from Serbian fans, but received praise for maintaining his conduct amid provocation.

During the semi-final against the Netherlands, he limped off with an injury and England were down to ten men as all three of the permitted substitutions had been made; they lost 13–12 on penalties.