Stephen Holt added 13 points and Brad Waldow 12 points and 12 rebounds for the Gaels (24-5), who never trailed.
Doug McDermott scored 22 points and Gregory Echenique 18 for the Bluejays (22-7).
Saint Mary’s won the rebounding battle 39-27.
The Gaels scored the last eight points before halftime to take a 38-24 lead. The 29.6 percent shooting for Creighton in the first 20 minutes was its lowest in any half this season.
A three-point play by Doug McDermott cut the Saint Mary’s lead to 43-34 with 15:21 to play, but Dellavedova hit a deep 3-pointer to put the Gaels back up 12. The Bluejays got no closer than eight points the rest of the way.