Victory moved Arsenal just back into the top four of the Premier League table and left Leicester City five points adrift from safety at the bottom of the table, but there was still a feeling Nigel Pearson emerged from this with more comfort than Arsene Wenger.
The result is of course all important, but this was not a comfortable night for Arsenal and the cheers were more of relief than celebration from the home fans at the end.
Leicester manager Pearson was reportedly fired and rehired at the weekend so had a lot to prove from a game where they were expected to get thrashed, while Wenger was reeling from a rare derby defeat by Tottenham.
Pearson set up his basement team to defend and hope to nick something. That meant playing five across the back including debuts for central defenders Robert Huth, a deadline deal loan signing from Stoke, and summer capture Matthew Upson.
It started well for the Foxes with Arsenal stuttering after their poor show at Tottenham and Riyad Mahrez tormenting the home defence.
The Algerian international, fresh from African Cup of Nations duty, should and could have scored twice in the opening exchanges, with one effort deflecting off Nacho Monreal for a corner and the other going through the legs of goalkeeper David Ospina before whistling past a post.
Then Arsenal began to kick into gear with Mesut Ozil finally displaying some of the talents that persuaded Wenger to spend £42.5m (€50m) on him.
The German World Cup winner seemed more determined than usual and he started and finished a 25th minute move which ended with Schwarzer tipping the ball wide for a corner. Ozil took it and drilled the dead ball to the near post where central defender Laurent Koscielny left marker Wes Morgan for dust and finished with a neat half volley.
Mahrez then had another couple of half decent efforts including a curling shot just wide and a header which flew narrowly over the crossbar.
But Arsenal were not fazed and Ozil inspired their second goal four minutes before the break when he struck a left footed drive from 25 yards out.
Schwarzer could only parry the shot away and Walcott put his foot through the ball to bury a shot into the far corner of the net.
It seemed Leicester were already done for. Or were they? They resumed the match on the offence with lone striker Andrej Kramaric in the thick of it.
Kramaric had scored 28 for club and Croatia this season before his move and he showed why when he nearly scored with two good shots on the hour.
And he displayed even better finishing ability to tuck away his 61st minute goal, albeit the opportunity owing a lot to some comic Arsenal defending and a possible handball by Esteban Cambiasso in the build-up.
Now Leicester looked more likely to score the next and repeat the draw they achieved against Arsenal earlier this season. Kramaric had a great chance to pull if off too when he was sent clear by Mahrez only to try and chip the Colombia keeper when he needed to belt it.
Wenger tried to shore it up by bringing on Aaron Ramsey for Walcott only to lose the Welshman to an injury eight minutes later and the French coach was ultimately delighted to get the win his team needed.
Ospina 7, Bellerin 6, Mertesacker 6, Koscielny 6, Monreal 7, Coquelin 8, Rosicky 6, Walcott 6(Ramsey 73, Flamini 82), Cazorla 5, Ozil 8, Sanchez 7 (Giroud 68, 5).
Schwarzer 5, Simpson 5, Huth 5, Morgan 5 (Ulloa 81), Upson 5 (Wasilewski 59, 6), Konchesky 6, Mahrez 8, Cambiasso 6, James 6, Schlupp 5 (Nugent 86), Kramaric 8.