Zane Najdawi made a 3 to give The Citadel a 16-point lead with eight minutes left and his layup about three minutes later made it 65-53. Ross Cummings scored five points and Jordan Strawberry had four during a 9-0 run that trimmed Mercer's deficit to three points with two minutes to go, but the Bulldogs responded with a 9-2 spurt to make it 74-64 with 18 seconds left.
The Bears scored 10 of the last 12 points, capped by Strawberry's 3 just before the buzzer.
The Citadel hit six of their 14 3-pointers during a 26-3 run over nine-plus minutes to take a 56-43 lead with nine minutes left. Mercer missed eight consecutive field-goal attempts and went scoreless for seven-plus minutes over that span.
Kaelon Harris and Quayson Williams had 13 points apiece for The Citadel (7-13, 2-6 Southern Conference). The Bulldogs snapped a 13-game skid against Mercer and beat the Bears in Macon for the first time since a 50-15 win on Feb. 10, 1927.
Strawberry scored a season-high 22 points for Mercer (10-12, 3-6), which has lost three in a row. Cummings added 16 points, including four 3-pointers - both career highs.