After losing 3-1 in their league opener to Aston Villa, a goalless first half raised tensions among the visitors.
But Kieran Gibbs tapped in Theo Walcott's cross before Aaron Ramsey's 20-yard shot slipped by Volkan Demirel.
Olivier Giroud converted a penalty after Michal Kadlec's foul on Walcott to seal a morale-boosting win.
The home defeat by Villa, combined with the club's inability to add to the summer signing of 20-year-old Yaya Sanogo from Auxerre, had brought unseasonably early pressure on manager Arsene Wenger.

 

But, while fans' demands for activity in the transfer market will be fuelled by an injury to Laurent Koscielny, their fears of being left without Champions League group-stage football were dispelled by a strong second-half performance.
Even if Fenerbache produce a surprise four-goal winning margin in the second leg in London on Tuesday, the Turkish side may not take their place in the group stages.
The Court of Arbitration in Sport will decide the day after the return leg if they will be expelled from the competition and begin a two-year ban for match-fixing.
As it is, the severity of centre-back Koscielny's injury, suffered when a stray boot from Pierre Webo forced him off with a bloodied face, is likely to be the most pressing concern for Wenger.
Midfielder Jack Wilshere had already shaken off an early knock, before full-back Bacary Sagna was forced to fill in after Koscielny went off, revealing the lack of depth to the Gunners' squad.
It was the notable incident of a first half in which Fenerbahce allowed Arsenal plenty of possession, but the visitors could only craft a couple of brief glimpses of goal for Walcott.
Arsenal looked much more incisive after the break though and Ramsey's telling pass in behind the hosts' defence created the opener.
Walcott latched on to the ball before sending a low cross fizzing across Demirel's goal which a sliding Gibbs did well to turn in shortly after the restart.
Ramsey's shot shortly after was less precisely-placed, but its power sent it squirming through Demirel's gloves.
Those goals combined with Fenerbahce's toothless attack had taken the sting out of a boisterous atmosphere, and Moussa Sow wasted a rare chance to restore the decibel level as he headed over from former Liverpool and Chelsea midfielder Raul Meireles's cross.
Instead, after Wilshere had blazed over after a mazy run, a tiring Kadlec bundled into the back of Walcott to allow Giroud to slot home from the spot and surely put the tie beyond the Istanbul side.

LINEUP, BOOKINGS (4) & SUBSTITUTIONS (6)

Fenerbahce

  • 01 Demirel
  • 04 Irtegun (Gonul - 46' )
  • 06 Yobo
  • 22 Alves Booked
  • 24 Kadlec Booked
  • 05 Topal
  • 14 Meireles (Potuk - 82' )
  • 25 Emre
  • 07 Sow
  • 09 Webo Booked (Emenike - 62' )
  • 11 Kuyt

Substitutes

  • 23 Gunok
  • 02 Korkmaz
  • 77 Gonul
  • 16 Cristian
  • 26 Potuk
  • 88 Erkin
  • 29 Emenike

Arsenal

  • 01 Szczesny Booked
  • 03 Sagna
  • 04 Mertesacker
  • 06 Koscielny (Jenkinson - 33' )
  • 28 Gibbs
  • 07 Rosicky
  • 10 Wilshere
  • 14 Walcott (Monreal - 87' )
  • 16 Ramsey
  • 19 Cazorla
  • 12 Giroud (Podolski - 82' )

Substitutes

  • 21 Fabianski
  • 17 Monreal
  • 25 Jenkinson
  • 26 Frimpong
  • 44 Gnabry
  • 09 Podolski
  • 22 Sanogo
Ref: Rocchi
Att: 50,500

MATCH STATS

Possession59%41%90minsFenerbahceArsenal

Shots

913

On target

39

Corners

35

Fouls

98