In the summer of 2023, Nnamdi Collins negotiated with José Mourinho at AS Rom. However, he decided to join Eintracht Frankfurt instead, citing a better plan at the club. Initially, there were plans for him to be loaned out to Nürnberg, but Frankfurt needed him for their own squad. His decision has been validated as he quickly became a standout performer, with club icon Makoto Hasebe naming him the surprise of the season due to his outstanding performances.