The 22-year-old made his full debut for his parent club back in the 2008/09 season in a 1-0 win over Hull City after joining from Stoke City.
The Belgian made a further five first-team appearances, in the League Cup and the Premier League, with the Red Devils keeping clean sheets in four of the matches in which he featured.
The move is De Laet's fourth loan away from Old Trafford having had spells at Sheffield United, Preston and, most recently, Portsmouth.
Canaries boss Paul Lambert told the club’s official website: "He’ll be great for us. He’s young and one of his main strengths is pace and he comes from a great club where he’s played first-team football.
"He’ll come in and help the other lads out. He’s played a lot of first-team games out on loan last season and I’m sure he’ll do great for us."
The player, who is primarily a centre-back but can play across the back four, said: "I’m really pleased to be able to continue my development as a young player with Norwich, where the manager has given me a chance to come in and fight for a place in the Norwich team.
"I know it’s going to be very tough because the lads there have done really, really well and it’s going to be a big challenge to get into a team which is really used to winning and is a great, tight-knit group.
"The fans there are great as well. I remember the game at Portsmouth when Norwich went up and the fans were superb. You could see how much it meant to them and to the club to get back into the Premier League after some difficult years.
"I took a look at the fixtures when they came out this morning and I’m sure everybody can’t wait to get going. Every game will be very tough and competitive, that’s what the Premier League is all about."