Aaron Graham added 13 points and five assists for the Hatters, who have won three of their last four games.
Stetson (6-10, 3-2), which led wire-to-wire, took an eight-point advantage into halftime. The Hatters held a 67-57 lead before a 7-0 ETSU (3-13, 1-2) run midway through the second half cut the deficit to three, 67-64, with 2:43 left to play.
Pegg hit a layup to extend Stetson's lead to five, 69-64, at the 1:13 mark. A Lester Wilson free throw made it 69-65 with 42 seconds left but Stetson converted three straight free throws to seal it.
Stetson shot 50 percent (24 of 48) from the floor and 11 of 22 from deep.
Wilson scored 21 points and Jarvis Jones had 19 for the Buccaneers.