Sophomore Kellen Dunham hit a two-point field goal with 22 seconds remaining in regulation to tie the game, but the Wildcats (12-1, 1-0), led by forward JayVaughn Pinkston, outscored the Bulldogs 10-7 in overtime.
Dunham cut the lead to 74-73, with 15 seconds remaining in the extra period, as the Bulldogs then forced a Villanova turnover. However, Dunham missed a 3-pointer that led to jump ball on the rebound from senior forward Khyle Marshall.
Villanova guard James Bell came up with a steal on Butler's in-bounds attempt with six seconds remaining, and Pinkston iced two free throws to close out the game for the Wildcats.
Pinkston, who finished with a team-high 22 points for Villanova, had 4 points, 3 blocks, and 1 steal in overtime, and guard Ryan Arcidiacano (9 points) hit a 3-pointer to open overtime, giving the Wildcats a lead they would never give up.
"Tonight, in a close game like that, there's a lot of things that can go either direction that can change the game," Butler coach Brandon Miller said in a release. "Tonight, it didn't go our way."
The Bulldogs had to play the majority of the first half without Dunham and Marshall, who both picked up two fouls early, and had to rely on their bench for scoring. Freshman guard Elijah Brown responded to the challenge, scoring 13 of his career-high 19 points in the first half, including two key 3-pointers.
Dunham, who finished with 22 points on 7-18 shooting, shot an uncharacteristic 3-11 on 3-pointers. Barlow added 9 rebounds and 3 steals for the Bulldogs, and finished with 6 points.
The Bulldogs continue Big East play on the road at Xavier on Saturday.