The new two-year deal includes the option of a further year for the 28-year-old midfielder.
Manager Chris Hughton told Norwich's official website: "I'm thrilled he's signed a new contract and committed himself to the club for the next two years. He's got plenty of quality and experience which I'm sure he'll continue to bring to the squad like he has since he arrived at the club. He's missed a lot of pre-season this year but it's great to now have him back in training, fully fit and available for selection."
Fox added: "I'm delighted to be here for the next couple of years and now I can push on from what has been a very successful time for myself and for the club.
"To end last season by coming third in the player of the season award was really touching and I was humbled by the whole thing. The lads played really well last year and it was a collective effort from everyone. It's up to me to play as often as I can now.
"I'm now fully fit and have been for a couple of weeks. I'm nowhere near match fit but you only get that by training and playing games. It's up to me to take my chance when I get it. I've now got to impress the manager and show him why I should be in the team. I'm raring to go when I am called upon."