The Bears jumped out to an 11-0 lead and led 36-27 at halftime. The Lions (8-11, 2/3 Ivy League) turned up the defensive pressure and took their first lead at 51-49 on an Ampin three-point play with 4:48 left.
Columbia extended its lead to 57-49 on a 3-pointer by Brian Grimes with 2:26 remaining, completing an 18-3 run.
Brown (7-15, 1-4) shot 57.1 percent from the field (12-for-21) in the first half, but was limited to 5-for-20 shooting in the second half.
The Lions also outrebounded Brown 36-29.
Matt Mullery had 17 points and eight rebounds for the Bears. With 994 career points, Mullery will try to become the 23rd player in Brown history to score 1,000 career points on Saturday night at Cornell.