He goes straight into the squad for today's relegation six-pointer with Nottingham Forest at the Valley after joining on an initial loan before a permanent move.
Boss Phil Parkinson was delighted to snap up the 29-year-old.
"We're really pleased to get Matty on a permanent signing," said Parkinson.
"He's a quality footballer and an experienced player.
"I've said that there is a certain category of player we're looking for, ones with Championship experience, and Matty fits the bill."