Referee Mike Dean sent off Arsenal defender Laurent Koscielny for wrestling Edin Dzeko to the floor, and although the Bosnian saw his penalty saved, via the post, City - who last won in the league at Arsenal in 1975 - took command with first-half goals from James Milner and then a tap-in for Dzeko.
Arsenal, who lost more ground on the top four, regrouped after the break, but were not able to find a way back into the game, even when City captain Vincent Kompany was sent off with 15 minutes left for a two-footed tackle on Jack Wilshere.
There had been a security alert outside the stadium before kick-off, which saw police cordon off access to the approach roads for the best part of an hour following a suspect package in a car park nearby.
The game burst into life on eight minutes. Koscielny grappled Dzeko to the floor in the six-yard box, leaving the referee little option but to award a penalty and punish the Arsenal defender with a red card.
The home fans, though, will inevitably have felt a sense of injustice, which was appeased somewhat when Wojciech Szczesny pushed Dzeko's spot-kick onto the post with his legs - and gratefully collected the ball as it rolled back along the goalline.
City, though, took the lead on 21 minutes. Dean again infuriated the home supporters by awarding a free-kick for Lukas Podolski's challenge on Javi Garcia. The ball was quickly worked out to Carlos Tevez, and his intelligent pass into the Arsenal area split the defence as Milner ran through to smash the ball high into the top-left corner.
Just after the half-hour and it was 2-0. Milner turned provider and his low cross through the six-yard box was turned goalwards by Tevez. Szczesny made a fine reaction save at full-stretch, but could do little as the loose ball dropped to Dzeko who rolled it in, before displaying a T-shirt with a message to friends from his "neighbourhood" back home.
In the second half, Dzeko sent Tevez clear through the middle after breaking down the left, but Szczesny made a brilliant stop as the City striker tried to run around the Arsenal keeper. At the other end, Oliver Giroud headed over from six yards after Bacary Sagna's free-kick from the right.
The red card was out again on 75 minutes, this time shown to City skipper Kompany when he clattered into Jack Wilshere, although the defender's sliding challenge won the ball, his feet were raised. Walcott saw his effort hacked off the line by Joleon Lescott in stoppage time, but it was too little, too late for Arsenal.
Source: PA
Source: PA