Emergency services including Lancashire Police remain on scene and working with Traffic Officers and recovery contractors to clear the overturned lorry.
The motorway has been fully closed southbound since 10.40am between junctions 28 (Leyland) and 27 (Standish).
All trapped traffic has now been released past the scene under police supervision.
The M6 is expected to remain closed until later this afternoon as recovery work continues.
Police and Highways are advising motorists to allow extra journey time when travelling south of Preston today, with the motorway closure leading to congestion on local roads.
Delays are already building on the approaches and diversion routes, with M6 congestion back to Lostock Hall.
Diversion route details and guidance is as follows:
Road users are advised to follow the hollow black square diversion symbol on road signs.
- Leave M6 south at J28 , join the B5256 East.
- At B5256/A49 Jct , turn right onto the A49 south.
- At A49/B5248 Jct , turn left onto the B5248.
- At B5248/Central Drive jct , turn right onto Central Drive south.
- At Central Drive/Euxton Lane Jct. turn left onto Euxton Lane.
- At Euxton Lane/B5252 Jct, join the B5252 south.
- At B5252/A581 Jct, join the A581 west.
- At A581/A49 Jct, turn left onto the A49 south.
- At A49/A5209 Jct, turn right onto the A5209 west.
- At A5209/Beech Walk Jct, turn right onto the A5209 north.
- At A5209/B5206 Jct , turn right onto A5209 north.
- At A5209/M56 J27 Rbt , rejoin the M6 south.