League leaders Arsenal opened the scoring in the 61st minute through Noni Madueke, but seventh-placed Brentford equalised ten minutes later through Keane Lewis-Potter.
In added time, Viktor Gyökeres played a deep pass to teammate Jurriën Timber, but the Dutchman could not capitalise on the chance.
Arsenal remain top of the Premier League after 26 games, with 57 points. Second-placed Manchester City are now four points behind. Aston Villa are third, on 50 points.
