Despite a dominant spell of Arsenal possession, it was the Bees who broke the deadlock in the 13th minute courtesy of Bryan Mbeumo's brilliant finish.
The Cameroonian cut inside off the right flank and fired past David Raya at his near post following Mikkel Damsgaard’s superb interception in midfield. It was the eighth time this season that Thomas Frank's side had scored with their first shot in a PL match – more than any other side in the division.
The hosts came close to doubling their advantage in what was almost a horror moment for Raya, who spilled an innocuous-looking effort from Keane Lewis-Potter before eventually retrieving the ball.
However, it was Arsenal who struck next moments later when Mark Flekken could only parry Thomas Partey's effort into the path of Gabriel Jesus to nod home on the rebound and score a sixth goal in his last four appearances.
Arsenal turned the match on its head in the 49th minute, enhancing their reputation as set-piece specialists after Brentford failed to deal with Ethan Nwaneri’s corner and Mikel Merino was there to slam in the loose ball.
Mikel Arteta’s side scored a third goal four minutes later, and it was Nwaneri involved in the thick of the action again, as Nathan Collins could only head the 17-year-old’s cross into the path of Gabriel Martinelli to dispatch his strike beyond Flekken.
Frank’s men were struggling to recapture the intensity from their first-half performance, and Arteta’s side were largely in control of the second-half proceedings amid the backdrop of a subdued crowd inside the Gtech Community Stadium.
The Gunners ultimately saw out the closing stages with relative ease to move within six points of leaders Liverpool – having played a game more than Arne Slot’s side.
Meanwhile, Brentford must be sick of the sight of Arsenal after succumbing to a fourth consecutive home H2H defeat against their London rivals.