The top-seeded Raonic earned another trip to the San Jose title match with a 6-4, 6-2 defeat of No. 3 seed Sam Querrey of the United States.
Haas reached the final with a 6-3, 6-4 win over second-seeded American John Isner in the day's first semifinal.
Should Raonic prevail Sunday, he would become the first player to win the San Francisco-area event three consecutive times in the Open Era.
Haas is seeking his 14th career ATP Tour win, and first since the 2012 tournament in Halle, Germany.