Mike Mercer added 14 points for the ninth-seeded Bulls (20-11), who hope a strong showing this week could propel them into an NCAA tournament field already sure to be flush with Big East regulars.
It was the first Big East tournament victory in two appearances for South Florida since joining the league in 2005-06.
Next up, the Bulls face No. 22 Georgetown in the early game Wednesday. South Florida stunned the then-No. 7 Hoyas 72-64 on the road Feb. 3, a loss that was sandwiched between big wins for Georgetown over Duke and Villanova.
Will Walker scored 20 points to lead DePaul (8-23), which lost its final 13 games.