German team VfB Stuttgart are among those interested in signing the 27-year-old Nigerian midfielder this summer.
Onyeka is currently under contract with Brentford until 2027.
He is not the only club interested in signing Onyeka, as Burnley and Fiorentina have also expressed their interest in the player.
Onyeka already has experience playing in the Bundesliga, having played 27 times for Nigeria and appearing in 31 out of 32 games for his previous club FC Augsburg.
