The 32-year old Irish centre-back has been with the Eagles since joining from Ipswich Town in August 2012 and has now extended his Selhurst Park stay by a further two years.
"It's really pleasing for me and something I've wanted to do," he told the club's official website.
"I was entering the last year of my contract here, so I've been talking to the club for quite a while. Obviously we've both had other things to worry about, but we managed to come to an agreement last week and I'm genuinely delighted.
"Since the day I first came through the door a little over 12 months ago, Dougie Freedman and Ian Holloway have great to me and the fans have too.
"We had a lot of success last year and have had a difficult time this year, but I'm up for the challenge and it's something I want to be part of."
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