Allen Payne had 15 points and Tahj Shamsid-Deen added 14 for the Tigers (13-13, 5-10 Southeastern Conference) in a battle between two of the bottom three teams in the league standings. Auburn won both regular-season meetings.
The Gamecocks (10-18, 3-12) lost their third straight game despite getting 26 points from Brenton Williams. Williams made 5 of 9 3-pointers while Mindaugas Kacina scored 10 points.
Auburn made 25 of 48 shots (52.1 percent) to snap a two-game skid.
South Carolina fell behind by as much as 20 in the second half despite shooting 59.1 percent (13 of 22) after halftime.
The Gamecocks committed 20 turnovers but held a 36-25 advantage in rebounds, led by Michael Carrera's 13 boards.
The game turned into a foul-fest with 53 combined fouls and 60 free throw attempts. Auburn's Shamsid-Deen and Jordon Granger were also called for technicals in the second half.
The Gamecocks cut a 20-point Auburn lead in half late. Brian Steele hit a 3-pointer to bring South Carolina to within 75-65 with 3:16 left, but the Tigers then pulled away.
They made 25 of 35 free throws in the game.
Auburn's KT Harrell had an off night, making 2 of 8 shots and scoring 11 points, nearly eight below his season average. Shamsid-Deen and Dion Wade both hit three 3-pointers to help pick up some of his slack from the perimeter.
Outside of Williams, who scored 55 points in the two meetings, South Carolina made just 1 of 11 from 3-point range. Sindarius Thornwell was 2-of-13 shooting for four points, 10 below his average.
Shamsid-Deen hit three consecutive 3-pointers to push Auburn's 12-point halftime lead to 50-31 early in the second half.
Then he was called for a technical after a foul call. He went to the bench with four fouls and nearly 16 minutes to play and Auburn still up 18.
The Gamecocks cut the deficit to 53-42 within the next 75 seconds with a 10-3 run but couldn't get any closer until the final minutes.