The Hawks (6-8) led 45-33 at halftime before the Bonnies (7-3) stormed back behind Marcus Posley, who had 17 of his career-high 26 in the second half.
St. Bonaventure erased that deficit quickly, taking a 53-52 lead on a Posley 3-pointer with 12:57 left. But when it counted, trailing 81-80 with 24.4 seconds left after two missed free throws, the Bonnies only managed a rushed 3-pointer from the right corner. Ishaq Pitt made a free throw with four seconds left but the Bonnies had a turnover on the last possession.
Youssou Ndoye had 18 points and 12 rebounds, going past 500 boards for his career for the Bonnies, Dion Wright had 16 points and Jaylen Adams had 10.
Devon Walker and Ryan Andino had 12 each for Maryland-Eastern Shore.