The Dutchman, who was close to joining Everton in January before injury derailed the switch, has signed a four-year deal to become Chris Hughton's sixth summer signing
The 23-year-old becomes the latest arrival in a busy few weeks at Carrow Road, joining fellow new recruits Javier Garrido, Ricky van Wolfswinkel, Nathan Redmond, Carlo Nash and Martin Olsson.
Fer was close to joining Everton before a knee injury saw the move collapse, and Norwich manager Chris Hughton has spoken of his delight at capturing the midfielder.
"We are really pleased to have acquired the signature of a player with the qualities that Leroy has," Chris Hughton told the club's official website.
"He's a very versatile Dutch international and at 23 he has that pleasing balance of having acquired experience playing over 100 games in the Dutch League - but still having plenty of time ahead of him to continue his development as a player here with us at Norwich City."
Fer has played for the Netherlands on two occasions, and featured in every game for the Under-21s in the European Championship, which ended in the semi-final defeat to Italy.