The motorway’s westbound carriageway was at one stage fully closed at junction 29 due to the fire, although a single lane has since reopened.
West Yorkshire Police said the incident happened around a mile before junction 28, the turn-off for Morley.
A spokesman for West Yorkshire Fire and Rescue Service said the lorry had been carrying wooden boards.
Fire crews from Hunslet, Morley and Ossett were called to the scene at about 4pm today.
Highways England is warning that it could be late this evening before traffic conditions return to normal.