Emergency services were called shortly after 10.05am to the southbound carriageway between junctions 8 for Bishop’s Stortford and 9 for Newmarket.
The driver of a small vehicle transporter, which was carrying a white van, became trapped after the transporter overturned.
Paramedics tended to the man but sadly he died at the scene.
The northbound side of the M11 reopened earlier, but the southbound side is expected to remain closed for a number of hours.
This is while forensic examination work is carried out and a diesel spill is cleared.
Police are working hard with their  partners to turn around traffic trapped in tailbacks as fast as possible and to get bottled water to drivers.
Officers appreciate it is very hot and many people have been stuck for several hours.
Police are working hard to get drivers to their destinations safely and ask people to be patient and wait until instructed by police to turn around.
Do not put other people at risk by turning around without instruction or by driving on the hard shoulder and blocking access for emergency vehicles.
A diversion route is in place, please see https:///highwaysengland.co.uk/travel-updates/travel-alerts/ for more details.
Anyone who saw the collision or has dash cam footage is asked to contact the Serious Collision Investigation Unit on [email protected]
You can also speak to an online operator at https:///www.essex.police.uk between 7am-11pm or call 101.
Please quote incident 427 of today’s date