UNC led by 13 at half and never by fewer than eight from there, shaking off a cold start to the half and finishing at 52 percent shooting after the break.
Aaron Brown scored 20 points to lead BC, while all-ACC guard Olivier Hanlan scored 18. But Hanlan shot 5 for 19 from the field and had missed 12 of his 14 shots entering the final 8 minutes.
Johnson went 8 for 17 from the field and finished with nine rebounds. Meanwhile Paige again looked healthier after battling a foot injury and had playing through pain since January, turning in an all-around floor game with nine assists, six rebounds and two steals.
Freshman Justin Jackson added 12 points and hit two 3-pointers for UNC, which thumped BC on the boards (43-25) and scored 19 second-chance points.
It was a much better start to the tournament than a year earlier, when the Tar Heels fell behind big and couldn't rally in a loss to Pittsburgh that gave them a quick exit from Greensboro.
Boston College had won its last three regular-season games - including an upset of likely NCAA tournament team North Carolina State - after a 1-14 league start. Then BC rallied from six down in the final 2 minutes and used Hanlan's shot with 10.9 seconds left to beat Georgia Tech 66-65 in Tuesday's ACC tournament opener for a fourth straight win that matched its longest streak of the season.
They managed to slow the tempo enough to hang around for much of the first half, though the Tar Heels finally sped things up late in the half and used an 8-0 burst to stretch out the lead and take a 43-30 halftime lead.
Boston College: BC shot 40 percent, including 6 for 21 from 3-point range. ... BC committed just seven turnovers. ... The Eagles made 17 of 22 free throws.
UNC: Meeks' status for the rest of the tournament is unclear. ... UNC also played without freshman guard Theo Pinson, who was a game-time decision due to a sore left foot. He had recently returned from a monthlong absence after breaking that foot in January. ... J.P. Tokoto had nine rebounds. ... UNC shot 49 percent for the game.
UNC: Against fourth-seeded Louisville in the quarterfinals on Thursday.