Williams went 3-for-4 from the line, and Vaughn was 2-for-2 in an extra period in which neither team made a field goal. Georgetown went 0-for-8 from the field in overtime, with Austin Freeman missing a potential game-winning 3-pointer against tough defense from Rashad Bishop at the buzzer.
Vaughn finished with 16 points, nine rebounds, six assists and six turnovers for the Bearcats (16-8, 6-5 Big East), who had never beaten Georgetown until a 64-57 victory at home on Jan. 28. Cincinnati, which beat Notre Dame earlier in the week, has won six of eight.
Greg Monroe had 13 points, six rebounds and five steals for Georgetown (13-9, 4-7), which has lost six of seven.