Ty Lawson added 13 points and several key plays late for the Tar Heels (27-3, 13-3 ACC), who earned the top seed for next week's league tournament in Atlanta. North Carolina shot 53 percent for the game and led most of the second half for its sixth win in seven meetings with Duke.
Jon Scheyer scored 24 points for the Blue Devils (25-6, 11-5), while Kyle Singler added 23. But they never could overtake the Tar Heels once they fell behind midway through the second half, falling short in their bid to clinch at least a share of the league's regular-season crown for the first time since 2006.
North Carolina swept the Blue Devils for the second time in the past 13 years. The Tar Heels also won the ACC outright for the third time in five seasons.
While Hansbrough had another strong performance, it was Lawson — who had 25 points in the first meeting — who took control when the Tar Heels were clinging to a 70-68 lead with 3½ minutes left. First he drove into the paint and kicked out to Danny Green for a 3-pointer, then drove past Scheyer for a layup and drew the foul for a three-point play that made it 76-69 with 1:03 left.
Duke led 39-38 at halftime behind 15 points from Singler, who repeatedly found himself open on the perimeter as the Blue Devils penetrated and kicked out for open looks. But they didn't fare much better defensively than the Tar Heels, with both teams shooting 56 percent in the opening 20 minutes.
In the second half, however, only the Tar Heels were able to continue that kind of efficiency.