The northbound carriageway between junction 39, near Denby Dale Road, and junction 38, near Woolley, will remain closed until at least 5pm.
Nine cars came off the back of the transporter as it travelled northbound at around 10.25am.
Some of the cars ended up on the southbound carriage way.
One of the cars also slipped down the embankment.
Chief Inspector Paul Hepworth said: “We would ask drivers to be patient when travelling near to junction 39 of the M1 following an accident in which a car transporter lost its load of nine cars earlier today.
“Lane three of the southbound carriageway remains closed while work is carried out to repair a barrier.
“The northbound carriageway is completely closed between junctions 38 and 39 - traffic is being diverted.
“There will be some delays. We are estimating that this carriageway will not reopen until rush hour or after rush hour.”