The Billikens (24-2, 11-0 Atlantic-10), playing as a Top 10 team for the first time since Dec. 29, 1964, extended their school-record winning streak and remained with No. 1 Syracuse and No. 3 Wichita State as the only teams in the country without a loss on the road.
Sherrod Wright had a career-high 34 points for the Patriots (9-17, 2-10), which lost for the 11th time in 13 games and are still without a home win in conference play.
Loe hit consecutive 3-pointers to give the Billikens a 79-77 lead with 3:10 remaining in overtime, and Saint Louis would not relinquish the lead from that point.
The teams went to overtime in their earlier meeting, an 87-81 Saint Louis win on Feb. 1.
After Jalen Jenkins made two free throws with 5 seconds remaining in regulation to give the Patriots a 73-72 lead, Jett missed the first of two free throws with 0.9 seconds remaining after being fouled on a full-court dash to the basket. He made the second attempt, and George Mason's ensuing inbounds pass was knocked out of bounds to force the extra period.
George Mason took a 35-32 halftime lead when Bryon Allen stole an inbounds pass and hit a 3-pointer as the buzzer sounded.
The Patriots used an 8-1 run early in the second half to take a 48-41 lead. But the Billikens responded with a 6-0 run, culminating with two free throws by Austin McBroom after Patriots coach Paul Hewitt was called for a technical foul with 12:30 remaining for throwing his jacket in protest of an offensive foul called on point guard Marquise Moore.
Mike McCall, Jr. had 16 points, Jake Barnett added 14 and Loe and Dwayne Evans had 13 each for the Billikens.
Jenkins finished with 16 points and eight rebounds for the Patriots, who have lost eight times this season after leading at halftime.