Wayne Rooney converted from the penalty spot to give United a first-half lead before extending their advantage early in the second half.
Juan Mata then came off the bench to find the net twice and condemn Norwich to a fifth consecutive defeat.
Here, Sports Mole takes a closer look at the action between the two teams at Old Trafford.
On target: 11
On target: 2
Was the result fair?
There is no doubt that United deserved to come away with the spoils. The home side looked rejuvenated under the guidance of Ryan Giggs, while Norwich looked every inch a team that is destined for relegation.
Man Utd's performance
This was a contrasting display from the champions, labouring in the first half before turning on the style after the break. During the opening 45 minutes United struggled to cut open the Norwich defence despite having nearly all of the ball. If anything, this seemed to be as if the players were moving out of the dour shadow of David Moyes before adopting a fearless attacking style more associated with Giggs in the second half. The home side looked likely to score whenever they pushed forward as the game went on, and they could have had at least a couple of more goals come the final whistle.
The Canaries can be pleased with their first-half showing as they soaked up a lot of pressure from the hosts while frustrating them with an organised and disciplined shape. There was no shame going in 1-0 down at the break, but it all went wrong as soon as Rooney scored again early in the second half. From there the visitors went into meltdown, losing all determination and hope. Neil Adams has a tough job keeping Norwich in the top flight, and it looks like it might not be possible considering that their final two games of the season are against Chelsea and Arsenal.
Sports Mole's man of the match
Michael Carrick: United's metronome kept the ball moving throughout at Old Trafford while also putting his foot in when necessary. On a strange and emotional evening for the champions, they needed the calm head of Carrick in midfield to make sure that the basics were covered.
Javier Hernandez has a glorious chance to make it 5-0 deep in stoppage time, but the substitute somehow slid the ball wide of the post when he had only John Ruddy to beat. A surprising miss considering the Mexican's usual ruthless standards in those situations.
There was no drama from Lee Probert, who officiated calmly and without controversy. He could have sent off Steven Whittaker for bringing down Danny Welbeck inside the box for United's penalty, but his decision to keep the defender on was a rational one.
Man Utd: Giggs will take charge of United for a second time next Saturday at home to Sunderland.
Norwich: The Canaries continue their battle for survival next Sunday when they face a daunting trip to Chelsea.