The Demon Deacons (5-3) won their third straight game, following up their 76-73 victory over Iowa on Tuesday night.
Wake Forest led just 34-33 early in the second half but went on an 8-0 run to pull away, leading the Crusaders (0-6) by as many as 15 at 61-46.
McKie, a 6-foot-7 freshman, also had 11 rebounds for his third double-double of the season. He was 7 of 11 from the field and added two steals, one assist and one blocked shot in 32 minutes.
The Deacons also got 11 points from Ari Stewart.
J.T. Terrell, who scored 32 and hit the game-winning 3-pointer in a 76-73 win over the Hawkeyes, finished with six points. He did not start, after being late for a pre-game shoot-around, and was limited to 22 minutes. Wake Forest overcame 17 turnovers by shooting 52.8 percent from the field (28 of 53) and piling up a 37-28 rebounding advantage.
Holy Cross, which was playing its fifth straight road game, got as close as 66-60 with 2:03 to go.
Stewart answered with a 3-pointer for Wake Forest and McKie had four points in the final 33 seconds, including a layup with 13 seconds left, to clinch the win.