January addition Henrikh Mkhitaryan opened his account for the Gunners with the opening goal and a second from Aaron Ramsey capped a memorable night at the San Siro.
Goalkeeper and midfield:
David Ospina - 7 - Arsenal's cup 'keeper had fairly little to do, but when called into action made some important stops. With Petr Cech under scrutiny for less than impressive recent displays, there may be a chance for Ospina to stake his claim to be number one at The Emirates.
Calum Chambers - 7 - Hardly put a foot wrong and could've been an unlikely goalscorer but for a smart Gianluigi Donnarumma save. Much better from the ex-Southampton graduate.
Laurent Koscielny - 8 - Reminded the Arsenal faithful just what a talented defender he is on his day. Cleared everything in his path and weighed in with several key challenges to help earn his side a clean sheet.
Shkodran Mustafi - 8 - The German international was a strong aerial presence in the Arsenal defence and helped keep a talented Milan front line relatively quiet. His challenge now is to maintain this level of performance, starting with Watford this weekend.
Saed Kolasinac - 8 - After a sticky patch of form, Kolasinac seemed back to his best and was an absolute Rolls Royce for the Gunners down the left-hand side. There are however concerns about his fitness after he was forced off midway through the second half with an injury.
Granit Xhaka - 7 - A solid outing for the 25-year-old. Initiated several attacks with decisive passing from deep and won the ball back for his team on a few occasions. Another Arsenal player who will be tasked with keeping up this level of performance.
Aaron Ramsey - 8 - Completed Arsenal's win with a clinical finish in stoppage time in the first half. The Welshman rounded Donnarumma to tap into an empty net after latching onto a signature Mesut Ozil through ball.
Jack Wilshere - 6 - Not his best game by any stretch, but kept shape well in midfield and popped up with a few typical dribbles toward the final third. Was dispossessed in the same manner a few times, which will come as a disappointment to the 26-year-old.
Henrikh Mkhitaryan - 7 - Now off the mark for his new side, his deflected strike inside the 15th minute set the tone in Arsenal's win. A player who has been accused of 'going missing' in big games, a goal in Arsenal's most important game of the season could help him push on to new heights.
Mesut Ozil - 8 - Two assists for the German schemer, Ozil's incisive passing lead to Arsenal's two goals on the night. The Gunners rely heavily on Ozil's creativity in midfield, and when he performs like he did against Milan it's no wonder why he's held in such high regard.
Danny Welbeck - 6 - A typically hard-working display. Welbeck's running caused problems for AC Milan's back line all evening, unfortunately, he wasn't able to take any of the chances he was presented with.
Ainsley Maitland-Niles - 7 - Picked up where Kolasinac left off. Was a picture of composure and looked largely unfazed by playing at the San Siro. Impressive from the Gunners academy star.
Rob Holding - 5 - Brought on to batten down the hatches, hardly had sufficient time to make any telling contribution.
Mohamed Elneny - 5 - Similar to Holding, didn't have enough time from the bench to have a significant impact.