Gonzaga (21-3, 11-1 West Coast Conference) gained revenge for a Jan. 9 loss to the Pilots.
David Stockton and Angel Nunez also scored 13 points for the Bulldogs, who have a three-game lead in the West Coast Conference.
It was Gonzaga's seventh straight win.
Portland (13-11, 5-7 WCC) lost for the third time in four games. Ryan Nicholas led the Pilots with 15 points and 15 rebounds.