The new deal will keep the 30-year-old at the club until 2011.
He said: “I’ve been happy since I’ve been here for the majority of the time, so I’m happy that it is now signed, sealed and delivered.
“I hope to show the best of my abilities on the pitch.
“It is for another three seasons so I’m very happy with that. I feel good, I feel strong, I feel like I’ve got a lot of experience and hopefully it will all come together now.”
Roberts joined the Premier League club from Wigan in 2006.