The collision happened near the Brook Street Roundabout (Credit: Essex Police)
Essex Police believe the man, who was in his 60s, fell ill at the wheel before crashing between junctions 27 and 28 at around 10.30am on Thursday, 3 February.
“He was sadly pronounced dead at the scene and his next of kin have been informed,” said a spokesperson for Essex Police.
“His death is not being treated as suspicious and a file is being prepared for the coroner.”
No one else was injured during the collision.
The road was closed for several hours while emergency services responded to the incident.
For more on this story, and the latest on our other local and national news, listen to Time 107.5FM
Tags: Brentwood, M25, Essex Police, Fatal Collision