Emergency services rushed to the scene between junctions 8 (Chorley) and 6 (Horwich) at around 3.55am.
Highways officers stopped traffic on the southbound carriageway while fire crews from Lancashire tackled the blaze.
Pictures from the scene show the van engulfed in flames on the hard shoulder, just half-a-mile from the exit at Middlebrook.
At around 4.43am, crews managed to extinguish the fire and recovery crews were called to the scene.
But due to damage to the road surface and barrier, two lanes of the motorway remained closed whilst repairs were made.
The motorway was fully reopened at 6am and no injuries have been reported at this stage.