Kevin Pangos added 15 points and eight rebounds for the injury-plagued Bulldogs (13-2, 3-0 West Coast Conference). Starting forward Sam Dower Jr. played sparingly as he continues to recover from a back injury, while Pangos is hampered with turf toe. Starting guard Gary Bell Jr. is out with a broken hand.
Gonzaga has won three straight games since losing to Kansas State. The Zags have won 21 straight WCC games spanning three seasons.
Saint Mary's (10-4, 1-1) played without coach Randy Bennett, who is serving a five-game suspension for NCAA violations. Assistant coach Eran Ganot led the Gaels, who were hurt by poor shooting.
Saint Mary's in the past decade has battled Gonzaga for supremacy of the West Coast Conference, and the teams have met in the past five WCC tournament title games, with the Gaels winning two.
Beau Levesque scored 12 points to lead Saint Mary's, which shot 31.9 percent in the game, while Gonzaga shot 49 percent. The Gaels made 1 of 12 3-point attempts.
Angel Nunez added 13 points and Kyle Dranginis had 12 for Gonzaga, which outrebounded the Gaels 39-22.
It was Gonzaga's second straight outstanding defensive game. The Zags beat San Francisco 69-41 on Monday.
Bennett will miss the next three games, serving a suspension announced last March for failing to properly monitor the basketball program and other issues.
Levesque scored four of Saint Mary's first five baskets as the Gaels took an early 10-7 lead.
Pangos hit a 3-pointer as Gonzaga went on an 11-2 run for a 19-14 lead.
Saint Mary's got within 19-18, but the Gonzaga defense clamped down. The Zags scored 10 straight points, including two 3-pointers by Drew Barham, for a 29-18 lead.
Saint Mary's was held to one field goal and two free throws in the final 7 1/2 minutes of the first half and trailed 36-22. The Gaels shot 32 percent in the first half and missed all eight of their 3-point attempts. The Zags shot 52 percent and won the first half rebound battle 23-10.
The teams traded baskets early in the second half, with Saint Mary's unable to reduce its deficit.
Saint Mary's did not make a field goal for more than 5 minutes, and Barham and Pangos hit 3-pointers as Gonzaga pushed the lead to 48-31.
The Gaels went more than 8 minutes without a field goal in the later stages of the game to fall behind 66-40.
The Gaels, who average 77 points per game, won their first nine games of the season, dropped three straight at a tournament in Hawaii, then beat Pacific on Monday.
Gonzaga's last conference home loss was in 2011 to Saint Mary's. The Zags are 66-2 in WCC games in the McCarthey Athletic Center since it opened in 2004.