A headlight control system for use on a snow plow mounted on the front of a vehicle and a related method are disclosed that automatically, selectively illuminate the headlights of the vehicle in addition to the headlights of the snow plow only when the snow plow blade is in a down position such that it is not physically obstructing the headlights of the vehicle. The headlight control system and method only operate to turn on the vehicle headlights when the snow plow lights are turned on. The headlight control system and method are capable of operating both the low beam headlights and the high beam headlights of the vehicle in conjunction with the low beam headlights and the high beam headlights of the snow plow when the snow plow blade is lowered.