Arsenal scored three goals in just over seven minutes to overcome a stubborn Lille side and make it two wins from two to start their Champions League campaign.
Jurriën Timber broke the deadlock in the 64th minute before Eberechi Eze and Bukayo Saka struck shortly after to take the game away from the visitors.
It means that the Gunners have six points out of six in Europe after they narrowly beat Napoli in their opening game.
That victory came during an early-season period of dominance in which it looked like the Gunners could do no wrong.
Mikel Arteta's side won their first seven games of the season before suffering a chastening 3-0 defeat at Brighton and Hove Albion in the last game before the international break.
On their return after three weeks away, things looked to be going bad again on Saturday when James Justin gave visiting Leeds United the lead early in the second half.
But a quickfire double from Riccardo Calafiori and Bruno Guimarães ensured that the defeat to Brighton now looks like more of a blip than the start of something more concerning for Arsenal fans.
There was some bad news from Saturday, however, as Arteta confirmed that both Piero Hincapié and Martín Zubimendi suffered injuries in a post-match session.
The duo were scheduled to undergo scans on Monday to determine the extent of their respective ankle injuries.
Arteta said: "We had a training session planned after the game for the players that didn't have enough minutes, to get everybody [into] the recovery on Sunday and to get everybody in the rhythm and in two very unfortunate actions, we lost two players.
"Not great. We need to assess them today, they will have further scans to see how they are and then we will have the timeframe how long they are going to be out for."