It originates at Sparta on U.S. Route 70 (US 70), goes through the town of Monterey, and ends on the west side of Livingston along SR 85.

SR 84 begins as a secondary highway in downtown Sparta, in White County, at a junction with US 70/SR 1.

It then follows a northeasterly path to through some rural farmland before entering some mountains and crossing into Putnam County.

SR 84 then becomes very curvy before it intersects and becomes concurrent with US 70N/SR 24, where it becomes a primary highway, and enters Monterey.

It then continues northwest through mountainous terrain and farmland before entering Livingston.