SR 9 begins as a primary highway in Cocke County at the North Carolina–Tennessee state line near Del Rio, concurrent with US 25/US 70.

US 25/US 70/SR 9 then goes through some curves and cross French Broad River via the Wolf Creek Bridge.

When US 411 meets its northern terminus, SR 9 becomes secondary; US 25W/US 70/SR 9 then leave Newport and cross into Jefferson County.

Once across the line, SR 139 separates and turns south towards Kodak, and US 25W/US 70/SR 9 continue west to cross into Knox County.

The highway then has an interchange with US 11E/SR 34 in Carter (also known as Trentville), with US 11E joining the concurrency as they enter Knoxville.

US 11E/US 25W/US 70/SR 9 then intersect SR 168 (Governor John Sevier Highway) before crossing a bridge over the Holston River and having another interchange with I-40 (Exit 394), where SR 9 and US 25W run concurrent with the interstate for a short ways before concurrent with I-640 (Exit 385).

US 25W/SR 9 then leave Clinton and become curvy again before going through Medford to enter Rocky Top (Lake City).

Immediately afterward, they intersect the northern end of SR 116 and pass by Cove Lake, Cove Lake State Park, and Caryville Dam before leaving Caryville and entering Jacksboro.

The highway now crosses into La Follette, where they go straight through downtown and then US 25W/SR 9 separate from SR 63 and leave La Follette, where SR 9 becomes a secondary route for the rest of its duration and becomes very curvy again as the road enters mountainous terrain.