Ruben Amorim's side were the visitors to North London for the 500th competitive match at the Emirates, where the Red Devils sought to stretch their post-Erik ten Hag unbeaten run to eight matches.
Arsenal, on the other hand, were aiming for a fourth straight win across all competitions since the international break, but they ran into stiff resistance during a lukewarm first 45 minutes in the midweek clash.
Man United were effectively nullifying Martin Odegaard and Bukayo Saka as Andre Onana went into half time without being seriously troubled, but Mikel Arteta's men upped the ante in the second half, where their often unstoppable corner routines did the damage.
Firstly, an inswinging cross from Declan Rice was nodded into the far corner by Jurrien Timber for his first Gunners goal, before Thomas Partey nodded Saka's delivery back into the six-yard box, where William Saliba deflected the ball into the back of the net with his backside.
Arsenal beat Man United in four straight league matches for first time
Arteta's team were not short of opportunities to extend their lead as the game entered its dying embers, but they ultimately declared at two, and their victory was a particularly historic one.
By handing Amorim his first defeat as Man United head coach, Arsenal recorded four successive league victories over the 20-time English champions for the first time in their 138-year history.
A 3-2 Emirates triumph in January 2023 kicked off that sequence for Arsenal, who also ran out 3-1 home winners in the 2023-24 campaign before a slender 1-0 success at a rainy Old Trafford later that year.
Arsenal made their feared set-piece routines count despite the absence of chief set-piece threat Gabriel Magalhaes, who ceded his place in the backline to Jakub Kiwior after coming off injured at half time against West Ham United.
Riccardo Calafiori was also nowhere to be seen in the matchday squad, allowing Oleksandr Zinchenko to earn an increasingly rare start at left-back, but Partey and Mikel Merino were both given the all-clear after their own knocks.
Will Gabriel, Calafiori be fit for Fulham?
Asked in his post-match press conference whether Gabriel and Calafiori would be able to face Fulham in Sunday's London derby, Arteta refused to rule either defender out of the trip to Craven Cottage.
"Gabi was a big risk to play today because he felt something against West Ham. Sunday is going to be a possibility with Riccardo as well, let's see how he reacts," the Spaniard said.
However, the Arsenal boss was also full of praise for the 'magnificent' Kiwior and Zinchenko, adding: "Big credit to Jakub and Alex, I think it's the first start for Jakub after a long time, you have to be thrown against this kind of opposition this kind of front players.
"The same with Alex, they did magnificently well so great. We trust them, they prepared so well, they had the opportunity and they grabbed it with both hands so very pleased for the team."
Arsenal's win coupled with Liverpool's 3-3 draw with Newcastle United means that they have cut the gap to the leaders to seven points, but they have slipped below Chelsea in the Premier League table on goal difference thanks to the Blues' 5-1 thrashing of Southampton.
Written by
Ben Knapton