The Scot, 28, has extended his stay at the Cardiff City Stadium until summer 2018.
Marshall joined the Bluebirds in 2009 following spells with Celtic and Norwich City.
"I'm delighted to have committed my future to Cardiff City," he told the club's official website. "I've had a fantastic four-and-a-half years here already.
"It's a privilege to be part of what we're trying to achieve and the fans have been brilliant to me from day one."
Marshall has made 25 appearances in all competitions for Cardiff so far this season.