Florian Jozefzoon has decided to join Derby County and reject a move to Leeds United, according to Sky sources.
The 27-year-old Dutch winger has already completed a medical with the Derbyshire club ahead of joining on a three-year deal.
Sky Sports News reported earlier on Thursday that Leeds had matched the Rams' £2.75m bid - both of which were accepted by Brentford.
Jozefzoon, who scored seven goals in 43 appearances last season, moved to Griffin Park from PSV Eindhoven in January 2017 and has just a year left on his current contract.
Brentford have already signed a replacement in Said Benrahma from Nice, with the Algeria attacker agreeing a four-year contract with a year's option on July 6.