The central defender beat Notts County goalkeeper Kevin Pilkington to a long Glenn Poole cross and saw his header loop into the net to earn his side a share of the spoils.
The Bees looked set for their first league loss since the beginning of November as they trailed for most of the match to a goal scored by striker Delroy Facey.
The forward reacted quickest to drill home after the Brentford defence had only half cleared following Matt Hamshaw's darting run into the box.
But Philips' late goal earned his side a point to keep them right in the promotion shake up.
The last minute drama took the spotlight off referee Stuart Atwell, who sent off Brentford striker Nathan Elder in the eighth minute.
The official, who awarded Reading a ghost goal in their game at Watford, deemed Elder had elbowed Michael Edwards when the pair went up for a header and sent the striker off.
County took advantage of their extra man and should have won the game.
Myles Weston wasted numerous chances shooting wide from the edge of the box, but he was not the only culprit.
Brentford goalkeeper Ben Hamer saved well from Jamie Forrester and the experience striker shot into the side-netting after rounding the Bees shot-stopper soon after.
Sean Canham wasted a late opportunity when Hamer smothered at his feet and also saw a header kicked over.
Marvin Williams went close for the home side first half volley but they offered little until Phillips' late intervention.