The man was working at a construction site near Double Ditch Road when the incident occurred just after noon.
Another worker manged to move the truck and free the man's crushed arm.
The unidentified man was taken to the Lynden Fire Station where he was stabilized before he was taken to St. Joseph Medical Center in Bellingham.
The man suffered serious trauma to his arm, according to fire officials. His condition was not known.
It was not known what caused the incident.