Waimate police said the truck, which was carrying 26.5 tons of the sticky substance, rolled onto its side around 10:30 a.m. Monday on State Highway 1 and spilled its contents onto the roadway, the Timaru (N.Z.) Herald reported.
Senior Sgt. Mike van der Heyden said suction trucks were brought in to pump the molasses off the road.
"We didn't want to hose (the molasses) off because that would just make it runny and cause it to spread further," he said.
Van der Heyden said the truck veered off the left side of the road and got caught in a wet verge, causing it to roll onto its side when the driver tried to pull back onto the roadway.
The driver was treated at a nearby hospital for minor injuries to his shoulder.