The result has moved the Gunners onto 28 points from 14 matches, leaving them third in the Premier League table, seven points behind the leaders Liverpool, who dropped two points against Newcastle United at St James' Park.
Arsenal had the ball in the back of the Man United net in the fourth minute of the contest through Gabriel Martinelli, but the offside flag quickly ended the celebrations of celebrations of the home supporters at the Emirates Stadium.
Thomas Partey somehow failed to convert a inch-perfect near-post corner in the early stages, nudging behind from close range, and Arsenal's biggest threat in the opening 45 minutes came from set pieces, with a well-organised Man United frustrating the Gunners.
The away side came close to taking the lead in the final stages of the first period through Diogo Dalot, but the Portugal international's effort just fizzed wide of the far post, with the two teams entering the half-time break all square.
Arsenal took the lead in the 54th minute of the contest, though, with Jurrien Timber heading a corner from Declan Rice into the back of the net from close range, as Man United were made to pay for giving away another set piece.
It was the same story in the 73rd minute, as a Thomas header from a Bukayo Saka corner hit William Saliba and dropped into the Man United net from close range, giving the Red Devils a mountain to climb.
In a tale as old as time, two set pieces proved to be the difference, and Man United have now dropped into 11th spot in the table, with the Red Devils falling seven points off fourth-placed Manchester City in the race for the Champions League spots.
ARSENAL VS. MAN UNITED HIGHLIGHTS
Jurrien Timber goal vs. Man United (54th min, Arsenal 1-0 Man United)
Arsenal make the breakthrough in the 54th minute of the contest, as Timber heads a corner from Rice into the back of the net; the Gunners are so dangerous from set pieces, and the hosts now have the lead in North London.
William Saliba goal vs. Man United (73rd min, Arsenal 2-0 Man United)
Arsenal double their advantage in the 73rd minute of the contest, as a header from Thomas hits Saliba and drops into the back of the Man United net from close range; the Gunners score again from a corner.
MAN OF THE MATCH - DECLAN RICE
Rice provided the assist for Arsenal to take the lead early in the second period, but it was his overall performance after the break that earns him the man-of-the-match award at the Emirates Stadium.
The England international was a driving force for the Gunners in the second half, with his energy and work-rate transferring to his teammates, and he finished the match having won four aerial duels and boasting a pass success rate of 88%.
ARSENAL VS. MAN UNITED MATCH STATS
Possession: Arsenal 50%-50% Man United
Shots: Arsenal 14-5 Man United
Shots on target: Arsenal 6-2 Man United
Corners: Arsenal 13-0 Man United
Fouls: Arsenal 12-8 Man United
BEST STATS
WHAT NEXT?
Arsenal will be bidding to make it five straight wins in all competitions when they head to Fulham on Sunday afternoon, before returning to Champions League action at home to Ligue 1 team Monaco on December 11.
Man United, meanwhile, will look to bounce back from the first loss of the Amorim era when they welcome Nottingham Forest to Old Trafford on Saturday, before visiting Viktoria Plzen in the Europa League on December 12.
Written by
Matt Law