Having played football for the Haringey representative side, he trialled with Arsenal through the Rap Aid Academy. An e-mail invitation to trial with Chelsea, whom he had scored against for Arsenal, was missed by his father, and by the time it was found Adeyemo was on trial with Watford, whose youth system he joined formally in October 2018.[2][3] He started a two-year scholarship with the club's academy in July 2021.[4]
Adeyemo made his professional debut for Watford on 7 January 2023, coming on as a 75th minute substitute for Joseph Hungbo in a 2–0 away defeat to Reading in the third round of the FA Cup.[7][8] On 14 January, he made his league debut, coming on as a substitute for Vakoun Issouf Bayo in the 68th minute of an EFL Championship home game against Blackpool. Just four minutes later, he scored his first professional goal, opening the score for his side, who would go on to win 2–0.[9][10]