A penalty from Ryan Giggs, followed by a strike from Wayne Rooney and a brace courtesy of Javier Hernandez did the damage, before Aaron Hughes headed in a consolation for the visitors in the closing stages.
Below, Sports Mole has looked back over the action to determine if the result flattered the hosts in any way.
On target 12
On target 5
Was the result fair?
A scoreline that reads 4-1 really tells its own story. From the first whistle to the last United were well in control and if anything, should have won by a greater margin. Had the outcome been 6-1 or even 7-1, the Londoners could have a had few complaints.
Man United's performance
Fulham may have been very poor, but from a United point of view, you can only beat what is put in front of you and the home side did that convincingly. They created numerous chances and what will have impressed Sir Alex Ferguson is the fact that his side converted four of them. He will also be pleased to see Rooney get back among the goals following his recent spell on the sidelines with a knee injury.
If truth be told, not one Fulham player looked like they believed that they could win this tie from the very first minute. As a result, they got handsomely beaten by their hosts. At times they had spells in possession, but away from home the laid-back combination of Dimitar Berbatov and Bryan Ruiz in attack does not work. You need strikers who will work hard and that duo doesn't. United's defenders were given an evening off for most of the most.
Sports Mole's man of the match
Mark Schwarzer: He may have ended up on the losing side, but Fulham's defeat would have been even heavier had it not been for Schwarzer between the sticks. The veteran Australian made a string of decent saves, including one which saw Rooney's effort tipped onto the crossbar.
How often does the biggest error in a match occur after 40 seconds? Well, it did today. He may have been under pressure from Chris Smalling, but there was no reason for Hughes to stick his hand up in the air. Subsequently the ball struck his arm and Giggs converted the resultant penalty, which in turn put Fulham immediately on the back foot.
Mark Clattenburg was correct to award United a penalty so early, but he should have awarded them another shortly after when Damien Duff handled inside the area. Apart from that though, the referee gave a steady performance in what was not a particularly competitive FA Cup tie.
Man United: Ferguson's side are at home again on Wednesday night when Southampton make the trip to Old Trafford.
Fulham: The Whites have the luxury of home comforts on the same evening as West Ham United make the short trip for a London derby.