Starks was 5-of-10 from the field and hit 6-of-8 free throws, including five in the final 48 seconds to secure the seventh consecutive win for the Hoyas (19-4, 9-3 Big East).
D'Vauntes Smith-Rivera added 14 points for Georgetown.
JaQuon Parker led Cincinnati (19-7, 7-6) with 15 points. Sean Kilpatrick scored 12 points to go with six rebounds and Cashmere Wright had 12 points and three rebounds for the Bearcats, who outrebounded Georgetown 37-32.
Cincinnati erased a 12-point deficit in the second half and trailed 55-53 with 1:16 left in the game, but Starks and Porter combined for seven points from the free throw line down the stretch while Cincinnati managed only a layup by Wright.