Butler falls to 10-6, 0-4 in the Big East Conference.
Georgetown's Aaron Bowen deflected a pass from Butler's Alex Barlow that was picked up Markel Starks who immediately dished it back to Bowen for a crowd-silencing dunk to give the Hoyas their final lead of the game at 66-64 with 57 seconds showing in overtime.
It was Barlow who came up big for Butler late in regulation by converting both free throws after Bowen committed his third foul. Butler held its largest lead at three with 25 ticks to go in regulation.
Starks needed just 11 seconds to make one of his two buckets from beyond the arc to tie it at 60 and send it to overtime.
Neither team began well on the offensive end of the court. During the opening 10 minutes of play the Hoyas shot just 35 percent, while the Bulldogs were a putrid 18 percent-Georgetown held a 13-7 advantage.
Then seemingly a switch was flipped for as both teams improved to near 60 percent for the remaining 10 minutes as the Hoyas carried a 34-29 halftime lead.
D'Vauntes Smith-Rivera, an Indianapolis native, led Georgetown with 18 points on 7 of 16 shooting from the field and had five assists with seven rebounds.
The Hoyas jumped out early by scoring the opening four points to go on an 11-3 run during the first six minutes. They kept the Bulldogs at arm's length until 3:19 remaining in the game.
That is when Andrew Chrabascz made two free throws to give Butler its first lead of the night at 53-52.
Kellen Dunham led Butler with a game-high 21 points. The normally sharp-shooting guard was 6 of 19 from the field including 1 of 11 from beyond the arc. He was a perfect 8 of 8 from the free-throw line.
The loss is Butler's fourth in a row. It is now 1-4 in overtime games.