The victory put Creighton in the championship game of the Las Vegas Invitational against Arizona State, which produced an 83-68 win over Arkansas in the other semifinal contest.
Wisconsin held a one-point halftime lead and the Badgers were ahead by two as the game entered its final 8 minutes.
Wragge, however, hit a 3-pointer to boost the Bluejays in front and they led by as many as 12 points down the stretch.
Doug McDermott made only 10-of-23 shots but scored 30 points for Creighton, which improved to 5-0. Wragge had 17 points off the bench.
Wisconsin (3-2) was led by Jared Berggren with 27 points and seven rebounds.