With all eyes on former Montpellier favourite Olivier Giroud, returning to his old club just months after firing them to the title, goals from Lukas Podolski and Gervinho cancelled out Younes Belhanda's early penalty to earn Arsenal the points as they began a 15th straight season in the Champions League.
Montpellier battled desperately for an equaliser after the break but Arsenal survived to maintain their record of never having lost a European tie against French opposition in France.
"It was great to score again. I like these situations, it was a great pass by Olivier [Giroud] and I feel good in those moments," Podolski said.
"We played well in the first half but not so good in the second. But we got the three points and that is important. We know we can improve."
Two minutes later Arsenal struck again. Carl Jenkinson's low cross into the area was seized upon by Gervinho who guided the ball into the net from close range.
There were some anxious moments for Wenger, watching from high in the stands as he begins a three-match European ban for his behaviour towards match officials after Arsenal's exit against Milan last season.
Cabella's fine lob come back off the woodwork while Belhanda found himself in front of goal with 10 minutes left but only managed to fire his shot straight at Mannone.
Arsenal's assistant manager Steve Bould, thrust into the limelight for the night, said the Gunners had rode their luck a little after the break.
"We deserved to be in front at halftime but we looked a bit tired after the break and dropped a little bit and to be fair they played very well," he told Sky Sports.
