Brentford have completed the signing of Toumani Diagouraga on a three-year deal for an undisclosed fee from Peterborough.
The midfielder, 23, spent the second half of last season on loan with the Bees where he made 20 appearances.
Brentford boss Andy Scott told his club's official website: "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."
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."