Artur Boruc, who was caught out by an Asmir Begovic long ball last time the Saints were on the road, helped the Gunners on their way by presenting the Frenchman with an open goal
Following their dispiriting defeat to Manchester United before the international break, Arsene Wenger's Premier League leaders started brightly against their high-flying opponents, with Jack Wilshere and Aaron Ramsey both hitting the post.
|VIEW FROM THE EMIRATES
|By Jamie Dunn
Two sloppy defensive moments gifted Arsenal a victory over Southampton as Artur Boruc's comic attempts to evade Olivier Giroud with a pair of calamitous turns were punished by the France international, before Jose Fonte pulled Per Mertesacker's shirt late on to gift the Gunners a penalty which the striker duly converted.
Make no mistake though, Arsenal was brilliant at times and was good value for the win - and its place at the top of the Premier Leage table for another weekend.
Theo Walcott meanwhile came through his return from injury unscathed against his old club, which was bright in spells but never really troubled Wojciech Szczesny
An impressive collective response was typical of a Southampton side which remains third in the table - for the time being - but Giroud completed his brace and made it 10 goals for the season from the penalty spot after Jose Fonte pulled back Per Mertesacker at an 85th-minute corner.
Southampton was dealt a blow ahead of kick-off, which was delayed by 15 minutes due to disruption on the Piccadilly line, with news that center back Dejan Lovren was ruled out due to illness. Jos Hooiveld came in for his first Premier League appearance of the season.
Theo Walcott returned to the Arsenal bench following two months out with an abdominal injury, while Mertesacker was back at the heart of defense following his midweek goalscoring heroics for Germany at Wembley.
Wilshere replaced the suspended Mathieu Flamini in midfield and almost opened the scoring after 10 minutes when his deft, lofted effort bounced back off the post and into Boruc's grateful arms.
The same upright was tested via Ramsey's audacious backheel from Mesut Ozil's cross - but Boruc's post could not save him after a moment of madness in the 22nd minute.
Upon receiving a routine backpass from Nathaniel Clyne, he loitered terribly before an embarrassing attempt to turn Giroud resulted in the Frenchman stealing the ball and finishing into an unguarded net.
Southampton forced Wojciech Szczesny into his first save of the match after 32 minutes when Mikel Arteta miscued a clearance and Adam Lallana's speculative left-footer was pushed over. The Arsenal goalkeeper then reacted superbly to thwart Jay Rodriguez's snap shot.
Luke Shaw struggled through much of the first half with a leg problem and was replaced by Steven Davis, with James Ward-Prowse reverting to right back and Clyne filling Southampton's vacant left back slot.
The reshuffle did not interrupt the visitors' momentum as they resumed brightly and Lallana thudded a drive into Szczesny's chest, meaning eyebrows were raised when the same player made way for Dani Osvaldo in the 52nd minute.
Having labored under Southampton's trademark high press, Arsenal responded impressively and Ozil cleverly engineered space in the area to test Boruc at his near post.
Osvaldo called Szczesny into action at the end of a driving 74th minute run at the other end.
Walcott was afforded a rapturous reception on his introduction and might have given Arsenal breathing space when he fired wide on the break, before Giroud ensured a four-point lead at the summit with his composed spot-kick.