The 31-year-old's deal was set to run out at the end of the 2013-14 campaign, but the midfielder has now committed himself to the club until the summer of 2016.
Jackson, who moved to the Valley in 2010, has made 29 appearances for the Sky Bet Championship outfit this season, scoring four goals.
After signing the contract, Jackson told the club's official website: "I'm really pleased.
"We've been talking for a while and I was desperate to get it signed and get my future secure. I've always said I love the club and love being captain of the club and I just always saw my future here and nowhere else.
"So I was desperate to get it pushed over the line and I'm delighted to finally do it. It's two more years but after that hopefully longer because I'd love to finish my career here.
"The club has been great for me and I really feel part of the fabric of the place so, for me, there's no better place to be and as long as the club will have me I'll be happy to be here."