He has signed a contract extension at Crystal Palace to keep him at the club until June 2021.
Kelly, 28, has made 79 appearances for the Eagles since joining from Liverpool in 2014.
"Being part of a squad that's remained in the Premier League since I came, that's been a real challenge," Kelly said.
"We've had a great set of lads and we've got a great set of lads now. We added well to the squad so it's always been exciting being at Palace and I've loved the challenge of trying to stay in such a good league and really enjoyed my time here.
"As a centre-half, the experience is coming now. I've been given chance over the past couple of seasons to play there and I feel like each game I'm learning.
"Watching in the first couple of seasons the people in front of me, I've learnt a lot from them. When the chance has come for me, I've enjoyed playing with some top class defenders."