The Badgers (4-0, 1-0) trailed 10-7 at the half, but quarterback Alex Hornibrook, who struggled with long passes in the first half, found success on the Badgers' first series in the third quarter.
Hornibroo threw a 61-yard play-action pass to sophomore wide receiver Quintez Cephus to the Northwestern's 11-yard line. Freshman running back Jonathan Taylor rushed for an 11-yard score on the next play for a 14-10 advantage.
The Badgers padded their lead to 21-10 with an assist from freshman receiver Danny Davis, who caught a 32-yard Hornibrook pass and eluded five Wildcats defenders to reach Northwestern's 6-yard line. He then hauled in a 5-yard pass to collect his first career touchdown at 5:26 of the third quarter.
Wisconsin extended its edge to 24-10 on a 23-yard field goal by senior kicker Rafael Gaglianone with 11:12 left in the game.
Taylor rushed 19 times for 80 yards and two touchdowns. Hornibrook completed 11 of 20 passes for 197 yards, with one touchdown and two interceptions. Cephus finished with four catches for 99 yards, a career-high.
Wisconsin outside linebacker Garret Dooley recorded four of the team's nine sacks of Northwestern quarterback Clayton Thorson.
Thorson completed 29 of 45 passes for 219 yards, with three touchdowns and two interceptions for the Wildcats (2-2, 0-1). Freshman running back Jeremy Larkin led the Wildcats on the ground with seven carries for 37 yards. Junior receiver Flynn Nagel had five catches for 52 yards.
The Badgers' second-half dominance continued with a 36-yard interception return for a touchdown by senior safety Natrell Jamerson. Wisconsin senior outside linebacker Leon Jacobs put pressure on Thorsen, as the Badgers' increased its lead to 31-10 with 9:54 remaining.
The Wildcats posted a pair of fourth-quarter scores but they came too late to make a difference. Freshman receiver Ramaud Bowman had a 2-yard touchdown pass with 4:46 to go, and senior superback Garrett Dickerson hauled in a 6-yard TD pass with 2:53 left.
The Wildcats capitalized on a Badgers turnover at the start when sophomore cornerback Trae Williams recovered a fumble by senior punt returner Jazz Peavy on the game's first play. Williams returned the ball to Wisconsin's 24-yard line, setting up a 34-yard field goal by freshman kicker Charlie Kuhbander.
Taylor scored on a 7-yard run at 3:48 of the first, but the Wildcats pulled ahead toward the end of the half, when Thorson connected with slotback Carmen Green on a play-action pass and 1-yard score. The touchdown gave Northwestern a 10-7 lead with 2:38 left in the second quarter.
NOTES: Wisconsin senior TE Troy Fumagalli, who missed Saturday's game with a minor leg injury, was the team leader in catches (15) and receiving yards (236) entering the game. ... Northwestern senior RB Justin Jackson ran nine time for 25 yards. He is up to 4,402 career rushing yards, 83 yards shy of the school career record of 4,485 held by Damien Anderson (1997-2000). ... Wisconsin improved to 27-7 in Big Ten play in the last five-plus seasons. The only league team with a better record is Ohio State, which entered Saturday with a 32-2 record in that span.