Jonathan Crompton threw two touchdowns, Montario Hardesty ran for two more and Rico McCoy forced two fumbles as coach Lane Kiffin grabbed his first win over a ranked opponent.
After warming up in their traditional orange home jerseys, the Vols (4-4, 2-3 Southeastern Conference) took the field in Halloween-inspired uniforms.
South Carolina (6-3, 3-3) fumbled on its first two drives on a rainy night, having entered the game with only five for the season.
The Gamecocks began clicking on offense in the second half as the Vols sputtered. Stephen Garcia connected with Moe Brown on a 31-yard touchdown pass to cut the margin to 28-13 with 2:05 left in the third quarter, but it was too little too late.