Boss Chris Wilder had few complaints and will not be looking forward to coming up against Mitrovic any time soon.
"He shouldn't playing in the division," Wilder said. "He should be playing at Newcastle. He has made the decision to drop down.
"Mitrovic is an outstanding player and thankfully we won't be coming up against him in the next 11 games.
"He's going to the World Cup, Newcastle paid what for him? Â£15million. He should be playing in the Premier League.
"We were well beaten in the end. It is no disgrace getting beaten to a team bang in form, a team that has won every game at home since the start of November.
"I'd rather be here on a Tuesday night in London than being somewhere else in another league like we have been for the last six years."
Fulham boss Slavisa Jokanovic believes there is even more to come from his side: "We are fourth in the Championship, we are playing with confidence, we know we can beat all teams in the division.
"We have to be mentally strong and push hard for the next step. It's important we keep winning the games and the stats are less important."
Mitrovic crashed in his fourth and fifth goals since joining on loan from Newcastle and Tom Cairney added a third after the break as the Cottagers posted an 11th win out of 14 games and ninth in a row at home.
That run has catapulted Slavisa Jokanovic's men into the hunt for the top two and they trail second-placed Cardiff by only five points, with nobody in English football taking more points than Fulham in the last 10 games.
And with striker Mitrovic taking his tally to five goals in a Fulham shirt, Newcastle boss Rafael Benitez must be questioning his decision to allow the Serb to leave on January's transfer deadline day.
Visiting manager Chris Wilder also has problems to ponder as his side slipped to ninth and - although they are only three points off the top six - their play-off push seems to be stuttering following a fourth defeat in seven games.
Given the reverse fixture finished 5-4 to Fulham, there was little surprise that both sides had chances in the opening 20 minutes.
Billy Sharp should have put the Blades ahead in the 13th minute but he criminally put a free header from Mark Duffy's cross over before Jamal Blackman had to be alert to keep out Stefan Johansen's deflected effort at the other end.
The Cottagers began to turn the screw and they were eventually rewarded in the 32nd minute as Mitrovic continued his impressive streak.
Fulham worked the ball down well down the right, Ryan Fredericks beat his marker and sent a low cross in for the Newcastle loanee to ram home off the crossbar from close range.
United did have chances to get back into it but John Fleck's low effort was well saved by Marcus Bettinelli before Clayton Donaldson unbelievably fluffed his lines only two yards out from a corner.
And that proved fatal as Fulham were in no mood for mercy, doubling their lead in irresistible style in the 44th minute, with Johansen's brilliant throughball deftly poked home at the near post by Mitrovic.
The rampant Mitrovic almost grabbed a 15-minute hat-trick but he was inches wide when Ryan Sessegnon put on the after-burners down the left and teed up his team-mate.
Fulham did not let up after the break and made it 3-0 just after the hour when Cairney swept home following good work from Lucas Piazon.
Mitrovic was desperate for a first career hat-trick and had another effort go just wide as he did not connect cleanly with an 18-yard shot.
His and Fulham's work was done, though, and they added the Blades to a list of recent scalps that includes Wolves, Aston Villa and Derby.