The man was driving a car southbound when it was involved in a collision with a second car near Junction 10a for Wolverhampton at around 6am on Friday.
He was then hit by a van on the other side of the carriageway after getting out of his vehicle and suffered "multiple serious injuries".
Paramedics and police were sent to the scene and the motorway which was shut in both directions between Junctions 10 and 11 for Walsall and Cannock throughout the morning.
Shortly after 12pm the northbound carriageway was reopened, before the southbound carriageway and eastbound carriageway of the nearby M54 were reopened later on Friday afternoon.
Highways England warned drivers to expect delays of more than an hour, with at least six miles of congestion.
The initial crash involved a silver Vauxhall Astra and a silver Renault Clio.
Staffordshire Police is now appealing for anyone with information or dash-cam footage to come forward.
A West Midlands Ambulance Service spokesman said: “On arrival crews discovered two cars that had been involved in a collision.
"One of the drivers, a man, had then been involved in a second collision with a van, after he had got out of his car.
“He was treated for multiple serious injuries at the scene before being taken to Royal Stoke University Hospital for further treatment. The doctor travelled with the patient to help continue treatment en-route to hospital.
“Nobody else was injured in the incident.”
Anyone with information is asked to contact Staffordshire Police quoting incident number 79 of December 3.