The Volunteers (16-13, 8-6 Southeastern) never trailed and shot 52.2 percent, (24 of 46) becoming the seventh SEC team to shoot 50 percent or better this season against the Gamecocks.
It was just the second road SEC win of the season for Tennessee, but it kept the Volunteers in fourth place, tied with Alabama, as they try to get a bye into the quarterfinals of the conference tournament.
Tennessee won despite turning the ball over 21 times. The Volunteers had lost their other two games in which they gave away the ball at least 20 times.
South Carolina (10-18, 2-12) shot just 32.4 percent (22 of 68). With two games left in the season, the Gamecocks are guaranteed the worst record in the SEC for the second time in six seasons.
Tennessee has won 11 in a row over South Carolina and remains one of two teams fourth-year Gamecocks coach Darrin Horn has not beaten. Horn is 0-10 in his nine-year career against the Volunteers.
Tennessee jumped out to an 11-point lead several times in the first half, including after a Jordan McRae 3-pointer put the Volunteers up 27-16 with seven minutes to go until halftime.
But Tennessee couldn't stop its sloppy play. The Volunteers had 11 turnovers in the first half, including giving the ball away on three straight possessions in the final two minutes. A 3 by Bruce Ellington cut Tennessee's lead to 34-32, but Ellington missed another 3 at the buzzer that would have given South Carolina the lead at the half.
The Volunteers opened the second half on a 16-7 run, then after a three-point play by Anthony Gill cut South Carolina's deficit to 50-42 with 11:56 to go, Tennessee went on a 16-9 run that put the Volunteers ahead 66-50 with just over four minutes to go.
South Carolina had just 10 turnovers, but poor shooting did the Gamecocks in. It was their fifth game in the SEC shooting under 35 percent, including their loss earlier this month at Tennessee.
Brenton Williams scored 11 points and Gill added nine points. Starting forward Damontre Harris was in foul trouble all game, missing his only shot and having just one rebound in 11 minutes before fouling out.