The Scarlet Knights (13-10, 5-7 Big Ten) scored 15 points off 12 Wisconsin turnovers to secure their third straight win. Noah Fernandes contributed 17 points, and Clifford Omoruyi added 13 points and 13 rebounds.
The Scarlet Knights shot 59% on 3s (10 of 17).
Williams had not played a college basketball game in nearly two years (709 days) prior to being activated before Rutgers' game at Michigan on Feb. 3. The Iowa State transfer endured a season-ending Achilles injury last year and then had to sit out 20 games this season for violating the NCAA's gambling policy.
"I just kept working and staying positive," Williams said. "It's everything to play on this stage."
Rutgers coach Steve Pikiell said Williams adds an intangible beyond his ability to score and distribute.
"I love his personality," Pikiell said. "He's always smiling, he loves practice and he's given us a voice on the court. I'm thankful he's out there."
After the Badgers closed to 54-44 on a 6-0 burst, Rutgers countered with five straight points from Fernandes to move ahead 59-44 with 8:12 remaining.
Rutgers took advantage of 11 first-half turnovers by Wisconsin to build a 37-28 lead. It was the fewest points scored in the first half for the Badgers in a Big Ten game this season.
"They [Rutgers] were more aggressive than we were," Wisconsin coach Greg Gard said. "We were way to tentative. We didn't respond up and down the lineup. I'm disappointed how we reacted to the pressure. That's the biggest thing."
Wisconsin: Part of the Badgers' spiral is their inability to convert 3-pointers. They were just 5-of-21 against Rutgers after going 5-of-19 against Michigan and 3-of-19 against Purdue.
Rutgers: The Scarlet Knights have been buoyed by the return of Williams, who was out because of injury and NCAA eligibility. In his first two games prior to Saturday, both Rutgers wins, he averaged 12 points and 5.5 rebounds while shooting 42.9% from the field. His emergence has provided stability to a roster that has been plagued by offseason transfers and injuries.
Wisconsin: Hosts Ohio State on Tuesday night.
Rutgers: Hosts Northwestern on Thursday.