The Blue Devils outscored the Demon Deacons 6-2 over the final stretch to repel an upset bid.
Plumlee made 12-of-15 from the field, dominating inside while Wake Forest was trying to shut down Duke's outside shooting threat.
Seth Curry added 21 points and Quinn Cook had 12 for Duke (18-2, 5-2 Atlantic Coast Conference). The Blue Devils made only 2-of-14 from long range.
Devin Thomas led Wake Forest (10-10, 3-5) with 15 points.
Plumlee's final basket gave Duke a three-point lead and the advantage grew to five when Rasheed Sulaimon made a jumper with 32 seconds to play.