Florian Jozefzoon has agreed personal terms with Derby and is set to join them on a four-year contract.
The Dutch winger was undergoing a medical on Thursday evening ahead of a move to Pride Park.
Brentford accepted £2.75m bids from both Derby and Leeds United – and the player has opted to sign for the Rams.
West London Sport recently revealed that the Bees had rejected bid for Jozefzoon from Derby and that Leeds were also interested.
Derby subsequently had an improved offer accepted, prompting Leeds to also table a bid.
Jozefzoon, 27, moved to Griffin Park from PSV Eindhoven in January last year.
He has made 58 Championship appearances for the Bees, with 21 of them coming as a substitute, and has scored eight goals.
His current contract is due to expire at the end of the coming season.
Meanwhile, Brentford have sold John Egan to Sheffield United.
This post was last modified on 20/07/2018