SR 178 begins at an intersection with US 13 Business in the town of Exmore.

The business route heads south as Main Street northeast as Lincoln Avenue.

North of the boundary between the towns of Exmore and Belle Haven, the state highway crosses the Northampton–Accomack county line.

In the center of Belle Haven, the state highway meets the western end of SR 181 (King Street); SR 178 turns west onto Shields Bridge Road, which crosses Occohannock Creek on the namesake bridge.

Within that village, the state highway passes St. George's Church has a very short concurrency with SR 180, which heads northwest as Harborton Road and southeast as Pungoteague Road.