The Tigers (10-7, 3-0), tied atop the Ivy League standings with Harvard, won their fifth straight game.
Princeton won it from beyond the 3-point arc and at the foul line. Bray was 3 of 3 on 3-pointers. Will Barrett (10 points) and Mack Darrow were each 2 for 3 from long range. The Tigers finished 8 for 11 on treys. Columbia (9-9, 1-3) was 4 of 13.
The score was tied 50-50 midway through the second half. But Hummer, who scored 16 points, was 12 of 14 from the free throw line -- including 7 of 8 in the last 4:28. After Columbia cut it to 69-66, Hummer hit 3 of 4 foul shots in the last 0:08 to ice it.
Maodo Lo led Columbia with 16 points.
Gonzaga center Przemek Karnowski, who missed most of last season with a back injury, says he is returning for another year.
Wisconsin forward Nigel Hayes has withdrawn from the NBA draft and will return to the Badgers for his senior season.
Recruiting reporter Jeff Borzello has gotten grilled for his selections of underachieving and overachieving college basketball programs. He joins Phil Murphy to explain his rankings.