Kent Police have said the pedestrian was pronounced dead at the scene. The clockwise carriageway of the M25 between junctions 3 and 4 is likely to remain closed until around 11am.
Any witnesses or anyone with information are asked to contact Kent Police on 01622 798538.
More top news
Turning cloudy and windy but feeling mild at the weekend.
The Ukip leader also says his children his hid in a graveyard and were brought back by police.
Here's a borough-by-borough breakdown of the official figures.