David Stockton added 15 points and Sam Dower Jr. had 13 points for Gonzaga (14-2, 4-0 West Coast), which has won 22 consecutive WCC games spanning three seasons.
David Taylor scored 11 points to lead Pacific (9-5, 0-3), which has yet to win a conference game in its first season back in the WCC. The Tigers left the conference in 1971.
Gonzaga built a big first-half lead, frittered much of it away when Pacific got hot in the second half, and recovered for its fourth consecutive win. Gonzaga shot 69.2 percent, making 10 of 13 from 3-point range. Pacific shot 31.7 percent, but made 10 of 25 3-pointers, most in the second half.
Gonzaga made its first six shots, including four 3-pointers, to jump to a 19-5 lead. Barham hit three of those 3-pointers and scored 12 points.
Gerard Coleman hit Gonzaga's fifth 3-pointer for a 29-11 lead with 11:35 left in the first half.
Pacific went into a dry spell, scoring only two free throws during an 8-minute stretch, to fall behind 37-16 with 6 minutes left in the first.
Gonzaga led 46-25 at halftime, after shooting 14 of 22 (63 percent). Pacific was 7 of 28 in the half.
The Tigers shot much better to open the second half, but still trailed 57-35.
Then, Trevin Harris hit a 3-pointer to launch a 15-1 run that cut Gonzaga's lead to single digits. Consecutive 3-pointers by Taylor and Tony Gill cut it to 58-50 with 12:23 left,
The Zags scored four consecutive baskets, two by Kevin Pangos, to rebuild a 67-50 lead.
Shortly after, Pacific went more than 5 minutes without a field goal, and Stockton's 3-pointer pushed Gonzaga's lead to 76-59.
The game concluded an unusual stretch in which Gonzaga played four conference home games over eight days. The Zags don't play at home again until Jan. 23.
This is Ron Verlin's first season as Pacific's head coach after 25-year veteran Bob Thomason retired.
Gonzaga has not lost a WCC game at home since 2011 The Zags are 67-2 in WCC home games since the McCarthey Athletic Center opened in 2004.