Mikel Arteta's late winner ended bottom-club Queens Park Rangers' resistance as Arsenal finished a turbulent week with a vital victory.
Arteta poked in from close range after hitting the bar, as the returning Jack Wilshere helped Arsenal bounce back from defeats by Norwich and Schalke.
The winner came moments after QPR's Stephane Mbia was sent off for kicking out at Arsenal's Thomas Vermaelen.
QPR's Esteban Granero and Jamie Mackie spurned good injury-time chances.
England midfielder Wilshere played 67 minutes as he made his first senior Arsenal appearance for 17 months.
It has been a tough week for Arsene Wenger after his side's surprise defeats by Premier League strugglers Norwich and Champions League visitors Schalke were followed by a spiky annual shareholders' meeting, where fans questioned the club's ambitions.
But Arteta's winner, which came after Hoops keeper Julio Cesar magnificently saved Olivier Giroud's header at the start of a goalmouth scramble, moves Arsenal into fourth in the Premier League table.
QPR have only won once at Arsenal in 28 years. Strikes from Kevin Gallen, Bradley Allen and Andy Impey sealed a 3-1 win on New Year's Eve 1994. Danish midfielder John Jensen scored his only goal for Arsenal.
It was harsh on Brazilian Cesar who produced several superb saves to keep out the Gunners as the crowd grew increasingly restless inside the Emirates.
Ultimately the game turned on the sending-off of Rangers defender Mbia, who was shown a red card by referee Anthony Taylor when he senselessly kicked out at Vermaelen while lying on the ground having already won a free-kick.
The defeat leaves QPR still searching for their first league win of the season and bottom of the table.
But manager Mark Hughes can take huge positives from a compact defensive display that only unravelled after Mbia's dismissal.
In their next three matches, Hughes's team face Reading, Stoke and Southampton - all teams in the bottom half - and will take heart from their brave display.
Even after they were reduced to 10 men and fell a goal behind, the visitors refused to give up and perhaps should have had an equaliser through either Granero or Mackie.
Former Real Madrid midfielder Granero skewed wide after he was put clean through, before Mackie powered through a parting Arsenal defence only to prod his shot straight at Vito Mannone.
Wilshere's return aside, pre-match attention was focused on QPR substitute Anton Ferdinand's decision to wear a T-shirt in support of anti-racism group Kick It Out during the warm-up.
Ferdinand - found by the FA to have been racially abused by John Terry - had chosen not to wear one last weekend and, in a joint statement released with brother Rio, has urged the organisation to do more to stamp racism out of football.
The Gunners' man in the spotlight was Wilshere and, after his first touch was greeted with huge cheers, he looked the likeliest player to unlock QPR with his neat touches and inventive play.
Aaron Ramsey's free header looped on to the Hoops crossbar, before Wilshere's stinging 20-yard shot was spilled by Cesar.
Injury-hit Jack Wilshere made his first senior appearance for Arsenal in 524 days. He last played for the Gunners against Fulham on 22 May 2011.
However, QPR continued to pose a threat on the counter attack, particularly down the flanks where they sought to expose the space left by the Gunners' attacking full-backs Sagna and Andre Santos.
Brazil international Santos endured a testing night against Schalke and his perceived vulnerability was targeted by pacy QPR pair Shaun Wright-Phillips and Jose Bosingwa.
Bosingwa failed to pick out the waiting Bobby Zamora as Vermaelen came to the rescue, while Wright-Phillips spooned a cross wide.
Arsenal's frustrations were typified by Santi Cazorla wastefully smashing an inviting half-volley over the QPR bar before Arteta clinched a vital win.
QPR boss Mark Hughes on Mikel Arteta's winner: "The referee has absolutely killed it to allow their winning goal because Arteta was clearly offside on two occasions. I've been to see the referee and he has created some cock-and-bull story about Ryan Nelsen being off the pitch. I've no idea what he is on about because Ryan Nelsen at no stage went off the field of play. It has cost us the point."
On Stephane M'bia's red card: "He's obviously very upset. The frustration from our point of was the foul had been given our way."
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