The Wildcats (27-3, 15-2 Big East) will open play in the Big East tournament at noon Thursday at Madison Square Garden against the winner of Wednesday's game between the eighth and ninth seeds.
Villanova coach Jay Wright credited the way his team has played this season in loud arenas. The Wildcats lost only one road game in the league all season, at Creighton.
"Our play on the road has been incredible," Wright said. "You're not going to win any championships unless you can win on the road and I felt tonight was a great example. We were playing an outstanding team in a tough environment.
"It's a great accomplishment. We have great respect for this league and to win this league is really a hell of an accomplishment."
Bell, who was limited to 22 minutes by foul trouble, scored 12 points to reach 1,000 for his career.
"It's a testament to how hard we work and where we've come from," Bell said. "It's definitely a big accomplishment, but we can't stop there. We have to keep getting better as a team and take it as far as we can go."
The Wildcats, who led for the last 25 minutes, rode some hot shooting in the first half and stifling defense in the second to build a 71-59 lead on a layup by JayVaughn Pinkston with 1:24 to play. But Xavier's Dee Davis stopped the fans from heading to the exits by hitting back-to-back three-pointers to make it 71-65 with 1:02 remaining.
The Musketeers (20-11, 10-8) reduced it to a one-possession game at 73-70 with 21.1 seconds left on Semaj Christon's basket. But Hart and Bell pulled Villanova out of danger at the free-throw line.
Darrun Hilliard led the Wildcats with 19 points, 15 in the first half, and Pinkston added 15.
The Musketeers, who shot only 34 percent in the second half and missed their first 11 three-point attempts, played without starting center and top rebounder Matt Stainbrook (strained knee ligament). Christon scored 18 points, slightly above his average, but needed 22 shots.
"He was getting easy ones" in the first half, Wright said. "The best player can't get them that easy. So we just talked [at halftime] about playing more together as a team defensively in the second half."
However, even with the regular season in their pocket, the Wildcats won't let up in their season finale Saturday against Georgetown at the Wells Fargo Center.
"It's the next game," Wright said. "Playing games is fun, so we're going to be fired up to play and just try to get better."
History lesson. The Wildcats were a No. 1 seed in the 1997 Big East tournament but that came when the conference was split into two divisions, and they won the "Big East 6." They were tied for the regular-season title with Connecticut in 2006 and were the second seed.