SR 84 begins at the top of Allegheny Mountain, which coincides with the Virginia – West Virginia state line and the Eastern Continental Divide. The highway continues west as WV 84, which descends the west side of the mountain to its terminus at WV 92 in Frost. The state highway passes through a pair of hairpin turns as it descends to Townsend Draft. At the draft's mouth at Back Creek, SR 84 turns north and follows Back Creek to Mill Gap, where the highway turns east and follows East Back Creek through its water gap between Little Mountain and Lantz Mountain. The state highway turns north and follows the valley through the hamlet of Mill Gap to Meadowdale. There, SR 84 turns east and follows the Jackson River through Vanderpool Gap between Monterey Mountain and Back Creek Mountain to its eastern terminus at US 220 (Jackson River Road) in the hamlet of Vanderpool south of the Highland County seat of Monterey.
