Knoxville, TN – Markeshia Grant had 27 points as South 60 victory.
La'Keisha Sutton had 12 points and six rebounds for the Gamecocks (18-5, 7-3 SEC), who are winners in four straight games.
Glory Johnson had 13 points and nine rebounds and Ariel Massengale donated 12 points for the Lady Vols (16-6, 7-2), who lost an SEC game at home for the first time in close to three years.
South Carolina was trailing by five, but Ashley Bruner put in a basket with just over three minutes to play to spark a 9-0 run, during which Tennessee missed five shots.
It was the Gamecocks' first win over a top-10 team since a victory over then- No. 6 Vanderbilt on January 3, 2002.