Campbell, who recently replaced the departed Dejan Stefanovic as skipper, told the club's website: "I'm delighted to have signed a new contract.
"It's dragged on a bit but everything's been resolved. There's always a bit of speculation around the transfer window but thankfully that's over now and I can just concentrate on playing football.
"The club's moving forward with a talented squad and plans for the new training ground. The club is certainly going in the right direction."