Allen had scored 15 by halftime and the Bulls (5-1) had led for 14 of the 20 minutes but trailed 37-36 at the break.
After halftime, South Florida notched five of its eight steals as well as five of its eight blocked shots to stymie Jacksonville (2-5).
Ruben Guerrero blocked four shots, including one with his elbow as the Bulls launched a 9-3 run to open the second half, and went on a 12-2 spree later in the period. It's the second straight game USF has come from behind after halftime to win.
Andris Misters scored 18 to lead the Dolphins, just six after halftime. Jacksonville outrebounded the Bulls 42-37 and had a 15-3 edge in second-chance points to stay in it.