Adeyemi was born in Milton Keynes, moving to Norwich with his family at the age of five after his father started a job in the area.

[5] He grew up supporting the club and was a season ticket holder alongside his father and grandfather before joining the playing staff.

[9] Having progressed through the youth ranks, he signed his first professional contract in November 2008 and made his debut for Norwich's first team on 8 August 2009, as a substitute for Matthew Gill during their heavy 7–1 defeat to Colchester United on the opening day of the 2009–10 season.

[10] Manager Glenn Roeder, who gave him his professional contract, described him:[11] "He's very athletic, technically very gifted and one of the nicest young men that I've ever dealt with.

[12] He made seventeen appearances for Norwich during his first season,[13] helping the club win promotion to the Championship, and was rewarded with a new contract set to run until 2012.

[18] During Oldham's FA Cup third round tie against Liverpool at Anfield, Adeyemi claimed he was the target of racist abuse from an individual in the stands.

Manager Lee Clark described him as "a terrific young lad who is a powerful and athletic midfield player who can get forward and score goals.

[32] In the latter part of 2013, Birmingham went ten games unbeaten with a team built around a "spine" of Adeyemi and loanees Kyle Bartley, Dan Burn and Jesse Lingard, but the loanees were recalled, Adeyemi suffered a back injury which appeared to restrict his physicality when he was fit to play, and the team struggled.

[33][34] He was able to produce a strong performance on the final day of the season, when Birmingham avoided relegation on goal difference.

[37] Adeyemi signed a three-year contract with Championship club Cardiff City, managed by Ole Gunnar Solskjær, on 7 August 2014.

[40] On 26 December, Adeyemi scored his first goal for Cardiff with a header that earned his team a point in a 1–1 draw with Charlton Athletic.

[42] However, he fell out of favour following Solskjær's dismissal and struggled to establish himself in the first team under new boss Russell Slade,[43] making just ten starts for Cardiff.

[44] On 14 July 2015, Adeyemi joined Championship rivals Leeds United on a season-long loan with the option of a permanent deal,[45] which would potentially be worth £1m.

[49] Having featured regularly during the first half of the season, he struggled for playing time following the appointment of Steve Evans as manager.

He made only two late substitute appearances in January, which led Evans to deny speculation that the loan spell could be terminated early and Adeyemi expressed a desire to fight for his place.

[5] He eventually made his first appearance for the club as a substitute in place of Flynn Downes during a 2–1 defeat to Queens Park Rangers.

[59] After three further months out, Ipswich manager Mick McCarthy confirmed that Adeyemi would miss the remainder of the 2017–18 season,[60] having made only five appearances throughout the year.