The 34-year-old damaged his anterior cruciate ligaments in the 2-2 draw with Preston in November and was forced to watch from the stands as Norwich failed to beat the drop.
But he saw a specialist on Wednesday and has been given the all clear to start training again.
"I'm feeling OK, it's been a difficult time over the last six months to be honest," he told the club's official website. "But I've done extra work with the two physios and I've been in the gym, and now I can't wait for the pre-season.
"It's been a difficult time, but I'm a mentally strong person anyway - this is my first major injury in my football career, but I'm totally ready now.
"I hope to stay here for another year and help this club get back to the championship. It's going to take hard work, quality, and with new players coming to the club, we'll go from there."