Northern Kentucky trailed 44-37 early in the second half before North Carolina went on a 12-3 spurt to blow open the game.
McAdoo scored 10 points during the decisive stretch, making three shots inside and hitting four consecutive free throws.
Tyler White scored 13 points to lead the Norse (4-8), whose three-game winning streak ended. Jalen Billups added 12 points, and Jack Flournoy and Jordan Jackson had 10 points apiece for Northern Kentucky, which shot 33 percent from the field, including 5 of 23 from 3-point range.
With his team leading 35-30 at halftime, North Carolina coach Roy Williams changed his lineup to start the second half. He surrounded Paige, the star point guard, with reserves Luke Davis, Isaiah Hicks, Jackson Simmons and Desmond Hubert.
The group responded with a 5-0 run, holding the Norse scoreless on six possessions. Hubert had an emphatic blocked shot on Northern Kentucky's second possession, and the Tar Heels later delivered their best team defense of the game.
Northern Kentucky hunted for a shot before settling for an off-balance 3-pointer by Anthony Monaco just before the shot clock expired. The shot failed to draw iron, and the resulting violation sparked a standing ovation from North Carolina's fans.
Northern Kentucky went more than 6 minutes before getting its first field goal of the second half, and the Tar Heels extended their lead to 12.
The Norse pulled within 44-37 on a 3-pointer by Monaco with 13:15 to play, but they never got closer.
The Tar Heels answered with seven straight points, six from McAdoo, to restore their double-digit lead.
Northern Kentucky started the game 1 of 13 from the field, and the Tar Heels pulled away as McDonald made three 3-pointers in a 3-minute stretch.
The Tar Heels had their biggest lead at 24-10 midway through the half before Northern Kentucky rallied behind White.
White scored on four drives into the lane and hit a 3-pointer in transition as the Norse scored on nine of 11 possessions.
Billups delivered a left-handed tip dunk to bring Northern Kentucky within 33-30 just before halftime.
P.J. Hairston, a swingman for whom North Carolina recently said it would not seek reinstatement, was not around. He watched the team's previous home games from the bench.