The Gunners opened the scoring through centre-back William Saliba and they doubled it before half-time as Gabriel Jesus struck with another header.
That was richly deserved for Arsenal, who were dominant throughout the opening 45 minutes, and they continued to impress after the break.
Fabio Vieira smashed home an effort from outside the box as he sealed the win and marked his first Premier League start with a goal.
Simon Collings was at the Gtech Community Stadium to see Arsenal in action…
Aaron Ramsdale – 6
Had very little to do really as Brentford struggled to offer much in attack. Distribution was decent and made one smart save late on to deny Mikkel Damsgaard.
Ben White – 7
Left out of the England squad this week but White continues to impress for Arsenal. Solid in defence and overlapped well on occasion.
William Saliba – 9
The Frenchman’s brilliant start to the season continued here. Unflappable in possession and opened the scoring with an excellent header.
Gabriel – 7
Seemed to be nursing a calf issue for most of the game, which he picked up in the warm-up. Did well considering as he battled with Ivan Toney.
Kieran Tierney – 8
Looks like he is now fully fit and the difference is clear to see. Was back to his usual self and bombing up and down the left flank.
Fabio Vieira – 8
Handed his first Premier League start due to an injury to Martin Odegaard. Was neat and tidy in the first-half, then scored a screamer after the break.
Thomas Partey – 8
Back in the side after recovering from a thigh injury and it was clear to see the impact he makes. So calm in possession and shielded the back-four very well.
Granit Xhaka – 9 | Star player
The best player on the pitch. He is in a rich vein of form right now and is relishing playing higher up the pitch. Capped off a fine performance with an assist.
Bukayo Saka – 8
After a slow start to the season the winger is starting to get back to his best. Looked very lively here and finished the game with two assists.
Gabriel Jesus – 8
Led the line so well against Brentford’s three big centre-backs. Took his goal really nicely by powering a header past David Raya.
Gabriel Martinelli – 6
A quiet game by his standards. Worked tirelessly on the left flank as always, though, and linked up well with Tierney – who got forward when he could.
Albert Sambi Lokonga (Partey 78’) – N/A
Eddie Nketiah (Martinelli 78’) – N/A
Takehiro Tomiyasu (White 86’) – N/A
Marquinhos (Saka 90’) – N/A
Ethan Nwaneri (Vieira 90’) – N/A
Subs not used: Turner, Holding, Sousa, Smith.