Rosen scored eight points and Bernardini six on a pair of 3-pointers during a 15-6 first-half run by the Quakers (9-9, 2-0) that gave them a 21-11 lead with 8:25 remaining in the first half.
Penn led 36-25 at the half and by as many as 16 points, 58-42, after a jumper by Rosen with 5:50 to play.
Bernardini made 3 of 4 shots from 3-point range and the Quakers were 10 of 20, while the Big Red (6-10, 1-1) were 3 of 17 behind the arc.
Shonn Miller led Cornell with 19 points, and he also grabbed 10 rebounds and blocked four shots.
Rosen had five assists and five steals for Penn, and Bernardini grabbed eight rebounds.