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.
Maryland point guard Melo Trimble, considered a lock to leave the program before struggling in the second half last season, has withdrawn from the NBA draft and will return for his junior season.
Louisville's Chinanu Onuaku, who recently underwent a medical procedure to correct a heart rhythm issue detected during the combine, will keep his name in the NBA draft pool.
Andrew White III will return to the Nebraska men's basketball team next season after removing his name from the NBA draft.