BK Ashe added 14 points for the Mountaineers (3-6), who made nine 3-pointers.
Bucknell took the lead in the opening minute and was up 44-30 at halftime. Mount St. Mary's grabbed its first lead with 6:20 left after a 10-0 run. Two baskets by Chris Wray put the Mountaineers ahead for good at 71-69 with 4:18 remaining. Robinson made two free throws and a jumper for a six-point lead and he added another basket and two free throws.
The Mountaineers came in as the nation's seventh-best team in turnover percentage and took advantage of 19 by Bucknell to score 22 points.
Bucknell (3-6) was led by Kimbal Mackenzie with 13 points. The Bison have lost five straight for the first time since 2009-10.