State Route 678 begins at a T-intersection with SR 374 in Hocking County's Laurel Township.

Turning to the east, SR 678 passes through the small hamlet of Gibisonville, where the highway is lined by a number of homes and a church.

Departing Gibsonville, the state route turns to the east-northeast, intersects Dunlap Road, then bends to the northeast.

At Mount Olive Road, SR 678 turns back to the east-northeast, passing a succession of homes and through more open space, before curving to the north at the Hocking County Road 9 intersection.

From here, SR 678 weaves through heavy woods, bending back to the northeast into an area of open space, prior to turning back to the north one final time before arriving at its terminal intersection at SR 180.