Emergency crews were called to Millfield Lane in Haydock shortly after 7am on Tuesday, May 13.
A police spokesman said the victim, believed to be in his 50s, suffered head injuries, a possible broken shoulder and leg and back injuries after being struck by an Isuzu truck.
Officers believe he may have been attempting to cross the road after parking up at the side of the road when the collision occurred.
The victim was taken to Fazakerley Hospital for treatment but his injuries were not thought to be life-threatening.
The truck driver stopped at the scene and is now helping police with their inquiries.
The collision led to the closure of Millfield Lane in both directions between the Haydock Lane and Andover Road junctions, near Haydock Lane Industrial Estate until about 11am.