The London derby burst into life almost immediately when Morgan Rogers put Chelsea ahead after just 77 seconds.
Rogers reacted quickest after a free-kick caused uncertainty inside Arsenal's defence and fired a low first-time effort beyond goalkeeper David Raya. The early goal gave Chelsea a dream start against the defending champions.
Arsenal quickly increased the pressure and thought they had equalised when Riccardo Calafiori found the net following a goalmouth scramble. However, VAR ruled out the goal after Ezri Konsa was judged to have been offside in the build-up.
Havertz Brings Arsenal Level
Arsenal continued to push forward and eventually got their reward in the 25th minute.
Former Chelsea striker Kai Havertz cut inside from the right before producing a composed low finish that beat Emiliano Martínez at the near post.
The equaliser changed the momentum of the contest, with Arsenal beginning to control more of the attacking play.
Chelsea remained dangerous on the counter-attack, however, and Pedro Neto came close to restoring the visitors' advantage when his effort struck the post just before half-time.
Ødegaard Completes the Comeback
Arsenal started the second half with renewed intensity and completed the turnaround in the 50th minute.
Christos Tzolis delivered the ball into the area, while Havertz cleverly allowed it to run through to Martin Ødegaard. The Arsenal captain made no mistake from close range, firing the ball into the net to give the hosts a 2-1 advantage.
Chelsea refused to surrender and continued searching for an equaliser. Arsenal goalkeeper David Raya was eventually called into action late in the game, producing an important save to deny substitute Estevao Willian.
Arsenal Maintain Perfect Start
The victory gives Arsenal their third consecutive Premier League win, keeping them alongside Manchester City as the only teams with perfect records at this stage of the campaign.
For Chelsea, the defeat ended their unbeaten start under new manager Xabi Alonso. Despite the loss, Chelsea showed attacking quality and created several opportunities, but defensive vulnerabilities ultimately proved costly.
Arteta's Side Pass a Major Early Test
The comeback represents an important statement from Arsenal in their title defence. Falling behind so early could have unsettled the champions, but Mikel Arteta's side responded with control, attacking pressure and composure.
Ødegaard's return to the scoresheet has also provided an encouraging sign, while Havertz's goal against his former club added another layer to an entertaining London derby.
