Tiera Stephen's layup in the closing seconds of the second half lifted Wisconsin over No. 7 Penn State, 63-61, at the Kohl Center.
Stephen finished with five points and 11 rebounds, while Morgan Paige netted a game-high 33 points and Jacki Gulczynski added 16 for the Badgers (10-11, 2-6 Big Ten), who have won two of their last three.
Maggie Lucas had 18 points to pace Penn State (17-3, 7-1), which had its school-record, 14-game Big Ten win streak snapped.
Mia Nickson and Dara Taylor netted 11 and 10 points, respectively, in defeat.
Wisconsin raced out to the early lead as Gulczynski sank three shots from beyond the arc and Paige added two more 3-pointers during a game-opening 17-6 run.
Penn State answered with a 6-0 push to get back within 17-12 before Wisconsin scored nine of the next 12 points to reopen a double-digit lead, 26-15, with 6 1/2 minutes left in the first half.
The rest of the half belonged to the Lady Lions, however, as they closed out the frame with an 18-3 run to carry a 33-29 edge into the break.
Wisconsin opened the second half with a 7-2 spurt to regain a one-point lead, but Nickson followed back-to-back 3-pointers by Lucas and Ariel Edwards with a layup to give Penn State back a 43-36 advantage.
The Lady Lions later held a 57-55 edge with about four minutes to play before Gulczynski followed a Stephen free throw with a jumper to go on top, 58-57.
Alex Bentley then connected on a pair of jumpers around a Paige trey to tie the game at 61-61 with 27 seconds left, but on Wisconsin's ensuing possession, Stephen grabbed the rebound of a missed Cassie Rochel jumper and laid in the game-winning basket with six seconds remaining.
Bentley missed a layup as the buzzer sounded at the other end to end the game.