Brentford have completed their eighth summer signing after Toumani Diagouraga joined from Peterborough United on Friday.
The 23-year-old Frenchman enjoyed a successful loan spell with the Griffin Park club last term and manager Andy Scott is delighted to welcome him back.
Speaking to the club's official website, he said: "It is no secret that Toumani has been a long-term target of mine and I am absolutely delighted that I have at last secured his services.
"I feel that at his age and his level of experience he will be a very important player for us both now and in the future.
Meanwhile, Diagouraga added: "I am really pleased that at long last I have been able to sign a contract with Brentford and that I can now concentrate on doing what I do best."