Rosen was 10 of 18 from the field and knocked down four 3-pointers.
Penn (11-9, 3-0 Ivy league) led 11-2 early in the first half and quickly pushed that lead to 34-18 following 3-pointers on four straight possessions.
Princeton (10-9, 1-2) cut the deficit to five, 46-41, in the second half behind seven straight points from Ian Hummer, but Rosen hit a 3-pointer and converted a three-point play to give the Quakers the lead for good.
The Tigers outshot Penn 57.8 percent (26 of 45) to 53.1 percent (26 of 49) but lost the battle of the boards 33-19.
The Quakers were 10 of 18 from 3-point range.
Hummer led Princeton with 21 points and has scored in double figures in 27 consecutive games.
- Beverley's big game helps Arkansas past Auburn 77-64
- NCAA gives North Carolina deadline to repeal HB2
- John Thompson III out at Georgetown after 13 seasons
- How will Kansas defend Caleb Swanigan and Purdue, the team built to beat it?
- Duke forward Jayson Tatum to declare for NBA draft
- March Madness 2017: Ranking the most compelling potential Final Four matchups
- Rawle Alkins has sparked Arizona with his toughness, winning mentality
- Michigan's March magic ends against Oregon's stifling defense
- Follow NCAA tournament Sweet 16 action
- The Vertical Mock Draft, Version 2.0
- Dillon Brooks' inextinguishable competitive fire has fueled Oregon's rise
- From immortal to quite mortal, Kentucky's Unforgettables face midlife challenges 25 years after their greatest moment
- Ranking this week's Sweet 16 games from most to least compelling