The Bears (17-7, 9-2 Atlantic Sun Conference) held the Spartans to just 5 of 22 from the field, including 0 of 8 from behind the 3-point arc in the first half.
Mercer trailed 6-2 early before running away with a 21-2 spurt. Jakob Gollon, who finished with 10 points, hit a free throw to put the Bears up 23-8 with 6:19 left in the first half.
SC-Upstate (14-9, 7-3) committed seven turnovers and missed all 12 of its field goals, including eight 3-pointers during the 10:32-long stretch.
The Spartans finished with 19 turnovers and just five assists. They shot 14.3 percent from 3-point range (3 of 21) and 31.5 percent from the field (17 of 54).
Ricardo Glenn and Torrey Craig led SC-Upstate with 13 points each.