Midfielder to remain with Sky Blues on loan until end of the season
"He has real potential to develop, making this deal one we’re really pleased to get over the line.
"James will return to on loan Coventry for the rest of the season to continue his development before joining up with us on a full-time basis in the summer.”
Maddison has to date already made 31 appearances for Coventry in his short career, including 13 for the Sky Bet League One promotion-chasers this season.
He made his senior debut as a 17-year-old in a Capital One Cup tie against Cardiff City in August 2014, and after netting his first professional goal against Oldham Athletic that October he has gone on to score three more times.
The Coventry-born youngster becomes the Canaries eighth signing of the January transfer window, following the recruitment of Matt Jarvis, Ivo Pinto, Timm Klose, Steven Naismith and Patrick Bamford, plus future prospects Ben Godfrey and Ebou Adams.
Maddison himself added: "I've been working hard towards achieving this goal and I'm delighted to be signing for a club the size and stature of Norwich.
"They are a club moving in the right direction and I'm looking forward to progressing my career there after finishing this season at Coventry."