The Bundesliga outfit officially unveiled the Nigerian international on Wednesday after securing his signature in a deal worth up to €10 million, including performance-related bonuses.
With Onyedika entering the final year of his contract at Club Brugge, Frankfurt moved quickly to land one of their long-term transfer targets on a five-year deal running until June 2031.
Sporting director Markus Krosche believes the 25-year-old's physical presence, tactical intelligence and consistency will strengthen a midfield that is being reshaped following the club's failure to qualify for European competition last season.
Onyedika is equally ambitious, insisting he wants to help Frankfurt return to the continental stage while competing for silverware.
"We want to try to bring the club back to Europe. I also want to win trophies," he said during his unveiling as quoted Soccernet.ng.
The midfielder revealed he has already settled into life in Germany, praising both his new teammates and the coaching staff for making the transition smooth.
"My new team-mates are amazing and have already helped me a lot. The coach is very approachable too. I want to help the team as much as possible. I want to play here and develop."
The move is also significant for Nigerian football, with Onyedika becoming the latest Super Eagles player to represent Frankfurt after legendary playmaker Austin "Jay-Jay" Okocha. The former Bolton Wanderers star remains one of the Bundesliga club's most celebrated foreign players.
"Everybody in Nigeria knows about Jay-Jay Okocha. He's a real legend in our country. Everyone knows about what he did at Eintracht and also in England," Onyedika added.
The defensive midfielder arrives after winning two Belgian Pro League titles, the Belgian Cup and the Belgian Super Cup with Club Brugge, while also making 24 UEFA Champions League appearances.
Having earned 26 caps for Nigeria, Onyedika will now be expected to play a leading role as Frankfurt aim to re-establish themselves among Germany's top clubs and secure a return to European football.
