An air ambulance has landed in a field next to the motorway.
Both police and paradmedics are at the scene.
A spokesperson for the National Highways said: “The M6 in Cheshire is closed northbound between J19 (Tabley, Knutsford) and J20 (Lymm) due to a serious collision involving a car and pedestrian which occurred shortly before 09:00 this morning.
“Emergency services including Cheshire Police, the North West Ambulance Service attended. North West Air Ambulance landed in an adjacent field to J19 roundabout.
“National Highways Traffic Officers are also providing assistance with traffic management.
“Cheshire Police will be carrying out investigation work, therefore the closure is expected to be protracted and in place for several hours today.”