The top-seeded Crusaders (22-10) advance to the championship game Tuesday against third-seeded Detroit.
Kevin Van Wijk and Erik Buggs added 11 points each for Valparaiso, which shot 54 percent from the floor and outrebounded the Bulldogs 39-22.
Fifth-seeded Butler (20-14) got 18 points from Chrishawn Hopkins and 12 from Erik Fromm. The Bulldogs shot just 33 percent overall and made 2 of 11 3-pointers.
The Crusaders used a 17-1 run early in the game to go on top 19-8. Butler pulled within 31-24 at halftime and opened the second half with another basket to make it a five-point game. But Broekhoff answered with a 3-pointer that started an 18-4 Valparaiso run as the Crusaders cruised to their third victory over the Bulldogs this season.