David Kravish added his fourth double-double of the season with 11 points and 11 rebounds. Justin Cobbs had 11 points and six assists and Cal coach Mike Montgomery moved into a tie for the third-most wins in conference history following the Bears' fifth straight win.
The Bears (13-4, 4-0 Pac-12) got off to a sluggish start before going on a 20-3 run midway through the first half.
Wallace helped spark the onslaught with a 3-pointer, an 18-foot jumper and a weaving drive through the lane layup. Cobbs added six of his points during the run while Richard Solomon scored on a dunk after the ball bounced off teammate Christian Behrens' back.
Cal never trailed after that while beating the Huskies for just the second time in the last six meetings between the two schools.
The Bears, who have not lost in nine home games this season, also improved to 4-0 in conference for the first time since 2009 Montgomery's first year at the school.
C.J. Wilcox scored 18 points for Washington. The Huskies (11-7, 3-2) were coming off an emotional win over No. 21 Colorado on Sunday but struggled on both ends of the court and suffered their most lopsided loss of the season.
It didn't start out that way.
California struggled against Washington's packed-in zone defense early and trailed 8-2 before going on its big run to move in front for good.
Washington's problems also extended to its offense.
The Huskies went through a pair of long scoring droughts that lasted more than four minutes each and shot only 24.1 percent in the first half.
Cal led by 13 at the break and pushed it to 47-26 following a four-point play by Jeff Powers, who was fouled after banking in a 3-pointer.
Powers and Wallace later added back-to-back 3s to help the Bears pull away.
Washington, which had allowed only six 3s in its first four conference games, allowed seven against Cal.
The game got chippy at the end when Cal reserve Sam Singer gave a hard foul on Washington's Darin Johnson to stop a fast break. Johnson had to be restrained by teammates as Singer waved to the crowd while walking toward midcourt.
Solomon finished with 13 points and 12 rebounds while Power scored 12 for Cal.