Parker led with a game-high nine rebounds and Thornton finished with seven as the Bulldogs went over the .500 mark for the first time since their season opener.
Georgia (5-4) held a pair of 10-point leads early in the second half but Gardner-Webb stayed within reach, even moving to within one point (38-37) with 6:32 left to play.
But the Bulldogs went on an 18-11 run in the final five minutes to hold off Gardner-Webb, which lost 85-66 on Monday to No. 8 Duke. Georgia has now won four straight after a four-game losing streak.
The contest was far from an offensive clinic, as Georgia shot 38 percent (18 of 47) from the floor and the Runnin' Bulldogs shot 31 percent (17 of 54). Georgia held a considerable advantage on the glass, outrebounding Gardner-Webb 46-27 -- the Bulldogs pulled down 32 defensive rebounds.
Georgia experienced a point drought of 5:35 in the first half, but scored the final eight points before the break as Nemanja Djurisic nailed a 3-pointer at the 2:25 mark and then connected on a layup with 1:51 remaining. Charles Mann closed out the scoring with 40 seconds left on a stickback to put the Bulldogs up 21-12.
Thursday's game was played in the late morning to accommodate some 5,000 Athens-Clarke County school children, faculty and staff.