Garino made 6 of 12 field goals and Jorgensen 6 of 10. A Tyler Cavanaugh 3-pointer a little more than three minutes into the game gave George Washington a 12-7 lead, which it held the rest of the way.
Garino has scored 17, 18 and 18 points in George Washington's first three games.
Although USF (0-3) came close at times, the Bulls could never regain the lead.
But Alex Mitola sank two foul shots with seven seconds left - the Colonials made 9 of 10 in the final 1:10 - and Nunez missed a final 3-point try.
McMurray scored 17 and Roddy Peters 12 for USF.