After delivering the game-tying goal in the 82nd minute, Arsenal edged Chelsea in penalty kicks.
Arsenal beat Chelsea on penalties to win the Community Shield and secure the first piece of silverware of the season.
After a goalless first half, the game came to life immediately after the break when Victor Moses gave the Blues the lead.
Chelsea looked set to hold on, but Pedro received a straight red card for a dangerous challenge late in the second half and Sead Kolasinac headed home from the set-piece that followed.
Olivier Giroud struck the winning penalty in the new shootout format to give Arsenal the first trophy of the new season.
In what was a rematch of the FA Cup final which ended last season (albeit one of less significance), it was Arsenal that began on the front foot, probing the Chelsea backline. For the Blues, who started without any of their new signings, it was something of a lethargic opening to the game.
Not until the 22nd minute did the first real opportunity present itself, Arsenal's new signing Alexandre Lacazette curling an effort past Thibaut Courtois after a one-two with Danny Welbeck but he was denied by the post.
Chelsea seemed to have not fully shaken off their pre-season rustiness, and there was a distinct opening game of the season feel for much of the first half. There was some improvement from the Premier League champions towards the end of the first 45 minutes, however, with Pedro testing Petr Cech with a powerful left-footed drive from just outside the box.
At the other end, Alex Iwobi demonstrated some quick feet to evade the challenge of Cesar Azpilicueta and tested Courtois, before Welbeck blazed a long-range effort emphatically over the bar.
Despite Chelsea's slow first half, it took just a minute after play resumed for them to take the lead, Moses ghosting into the box and latching on to a Gary Cahill header before beating the onrushing Cech.
It was a goal that came from nothing, but seemed to invigorate a previously lacklustre Chelsea side. In response, Arsenal offered some extended pressure, almost levelling through what was likely an unintentional - or maybe an incredibly audacious - effort from a tight angle by Mohamed Elneny, forcing Courtois to tip over.
With their narrow lead intact, Chelsea looked to retain their shape and contain the Gunners. Granit Xhaka attempted to take a more effective route to goal with 15 minutes remaining, unleashing a ferocious strike from distance and bringing a full-stretch save from Courtois.
But with ten minutes remaining, Pedro saw a red card for a dangerous challenge from behind on Elneny, before substitute Kolasinac brought the Gunners level with a header from the resultant free-kick.
The man advantage meant that the final minutes were spent largely in pursuit of an Arsenal winner, but it was actually Chelsea that came closest - Alvaro Morata, on for his debut, headed narrowly wide in injury time.
With no extra time, penalties were required, and in a slightly bizarre shootout that demonstrated a new format called ABBA, Arsenal kept their composure to emerge as winners.