Club Brugge will receive around €9 million for the Nigeria international, who has agreed to sign a contract with Frankfurt running until 2030 once he completes a medical early next week.
Eintracht Frankfurt had identified Onyedika as their priority target for the summer and had shown interest in previous transfer windows before finally agreeing terms with Brugge this time around.
Onyedika has been a mainstay for the Belgian champions since arriving from FC Midtjylland in the summer of 2022, making 183 appearances and contributing nine goals and six assists across four seasons in Bruges.
He won the Belgian league title twice, in 2024 and again this year, as well as the Belgian Cup and Belgian Super Cup in 2025, establishing himself as one of the division's most sought-after defensive midfielders.
The move brings an end to a saga that had dragged on for months, with Onyedika entering the final year of his contract at Brugge and having turned down several extension offers as he pushed for a move to a bigger league. Saudi Pro League side Al-Ittihad had also submitted a formal offer in an attempt to hijack the deal, but Frankfurt's long-standing relationship with the player and his representatives proved decisive in the end.
For Frankfurt, the signing addresses a clear need in central midfield after a disappointing 2025-26 Bundesliga campaign in which they finished eighth. Onyedika's arrival is intended to bring greater defensive stability to the middle of the pitch as the club looks to mount a stronger challenge next season under head coach Adi Hütter.
Nigeria's 26-cap international becomes one of the more notable African signings of the German transfer window, and Frankfurt will hope his experience and ball-winning qualities translate quickly to a higher level of competition than he faced in Belgium.
The fee represents a significant discount on Onyedika's valuation earlier in his Brugge career, when the club had been holding out for figures closer to €20 million before his contract situation weakened their negotiating position.
Brugge will look to reinvest the funds as they prepare for a new Belgian Pro League title defence, having decided in January they would sanction his departure if a suitable offer arrived. With personal terms never a significant obstacle, the transfer fee proved the only real sticking point before the two clubs found common ground this week.