[6] During the 2002–03 season, Okuonghae failed to make an appearance for the first team,[6] but was an unused substitute during a 4–1 win at home to Cambridge United on 18 January 2003.
[7] He made his professional debut for Rushden & Diamonds, now in the Second Division in 2003–04 as an 87th-minute substitute in a 4–0 win over Colchester United at Nene Park on 22 November, but did not feature again for the rest of the season.
[8] Okuonghae found himself playing in the first team more regularly during the 2005–06 season, making a late substitute appearance in a 1–0 victory away to Mansfield Town on 9 August 2005.
[5] Following an unsuccessful trial at Gillingham, Okuonghae joined Conference National club Aldershot Town in August 2006.
[11] In late August 2006, after just two appearances for Aldershot, Okuonghae joined St Albans City on a non-contract basis.
[12] Okuonghae moved on from St Albans in January 2007, representing his third Conference club of the season as he signed for Crawley Town.
[22] Although Dagenham & Redbridge had offered Okuonghae a new contract, he described his move to Colchester as a "no-brainer" and felt that he could make the step up to League One football.
[25] Having played every match for the club since his transfer, he captained the team following Pat Baldwin's injury in September 2009, and was rewarded with a new contract in December 2009 to keep him at the Community Stadium until 2012.
[32] In the latter part of the season, Okuonghae struck up a good relationship in the centre of defence with Tom Eastman, at one stage conceding just two goals in six matches.
[33] With his contract expiring in the summer, Okuonghae said that rumours linking him with a move away from the club "helps me to raise my game" and gives him the confidence to improve his performances.
[33] During a summer of uncertainty for Okuonghae, it was reported that a number of Championship clubs were keen on capturing his signature, including Blackburn Rovers, Bolton Wanderers, Burnley, Charlton Athletic, Derby County, Millwall, Sheffield Wednesday and Scottish Premier League club Celtic, having also been offered a new contract by Colchester.
[42] Following a solid start to 2013–14, Okuonghae was nominated for the League One Player of the Month award for August, having been an ever-present member of the Colchester defence that conceded just four goals in five matches.
[43] In a 4–1 defeat by his former club Dagenham & Redbridge in the Football League Trophy on 3 September, Okuonghae received his second red card of his Colchester United career.
[47] Okuonghae scored the opening goal in Colchester's first match of the season, a 2–2 draw at home to Oldham Athletic.
[51] In Colchester's 1–0 defeat at home to Coventry City on 22 November, Okuonghae suffered an achilles tendon rupture and had to be stretchered off the field late in the match.
[55] He made his debut for the club as a 59th-minute substitute for Scott Cuthbert in a 2–1 win at home to Leyton Orient in the Football League Trophy on 1 September.
[59] He returned to first-team football for Luton to make his second starting appearance in a 2–0 defeat away to Peterborough United in the FA Cup on 6 December.
[63] Okuonghae re-signed for National League club Dagenham & Redbridge on a short-term contract until 2 January 2017 on 25 November 2016.
[70] Okuonghae made his debut a day later, starting in a 1–0 away victory over East Thurrock United,[71] before finishing the loan with 10 appearances.