Harry Forrester has turned down the offer of a new contract at Brentford to sign for Doncaster Rovers.
As he is under 24, Brentford will be entitled to compensation should the transfer go through; a fee has yet to be agreed between the two clubs.
A Brentford spokesman said: "We would like to thank Harry for his service and commitment over the last two seasons. We wish him well for his future career.
"Whilst sorry to see Harry depart Griffin Park, it simply underlines the fact that whilst we as a club will move to attract and secure talented individuals, we only want players who are absolutely committed to Brentford.
"We will make very positive and aggressive offers to retain the services of key staff, but not seek to break the pay structures that we think are appropriate."
Forrester arrived at Brentford in August 2011 and played 68 games for the Bees over the course of two seasons, scoring 11 goals.
He will now have the chance to play at a higher level with Doncaster, after agreeing a deal that Sky Sports first revealed on Tuesday.