The winger took advantage of uncharacteristically static Arsenal defending to head past former teammate David Raya to cancel out Noni Madueke's opener.
It was a damning setback for Mikel Arteta's side, who still remain four points clear of nearest challengers Manchester City but this result will have been music to the ears of Pep Guardiola.
For Keith Andrews' Brentford, it was a magnificent display that enhances their chances of European football next season.
Keane Lewis-Potter scores Brentford's equaliser in their 1-1 draw against Arsenal (Image: PA)
They were fantastic from start to finish and could have easily celebrated with all three points.
Chances were at a minimum during the first-half but Brentford had a glorious opportunity to break the deadlock just after 20 minutes.
Mathias Jensen got the better of Declan Rice outside Arsenal's penalty area and his exquisite cross found Igor Thiago, but his header was kept out by former Brentford goalkeeper David Raya.
The striker knew he had spurned a glorious opportunity and it would have been a deserved breakthrough given Brentford's relentless start to the contest.
Arteta would have not been pleased with his side's first-half display and responded with a half-time change, taking off Ebere Eze for Martin Ødegaard.
Despite not being at their best, the Gunners would break the deadlock through Noni Madueke.
After a clearance found its way to Piero Hincapié, the left-back's pinpoint cross found Madueke to head Arsenal in to the lead.
It was harsh on the hosts, who had played so well up until the winger's opener but testament to their character they have shown all season, they were level 10 minutes later.
Arsenal's Noni Madueke (right) gave Mikel Arteta's side the lead. (Image: PA)
Michael Kayode's throw-in caused chaos in the penalty area, with Lewis-Potter taking advantage and heading past Raya to give Brentford the equaliser their performance merited.
And from all then, it was complete Brentford domination, with Thiago having two tantilsing opportunities to seal a famous victory.
The striker was set to pull the trigger, but an excellent last-ditch tackle by Cristhian Mosquera denied the striker.
The Brazilian generated too much power on another chance, with Dango Ouattara and Mikkel Damsgaard also close.
Gabriel Martinelli almost stole it for Arsenal at the death but was expertly denied by Caoimhín Kelleher.
Nonetheless, a point is a fantastic point as far as Brentford are concerned, although Andrews perhaps feels his side should have taken all three.
Next up for the Bees is an FA Cup tie at Macclesfield, before resuming league matters against Brighton next Saturday.
Brentford: Kelleher; Kayode, Ajer, van den Berg, Henry (Hickey 90); Yarmoliuk (Henderson 73), Janelt, Jensen; Ouattara, Thiago, Lewis-Potter (Damsgaard 73).
Arsenal: Raya; Timber, Mosquera, Gabriel, Hincapié (Calafiori 81); Zubimendi, Rice; Madueke (Saka 70), Eze (Ødegaard ht), Trossard (Martinelli 81); Gyökeres.
Attendance: 17,224