The No. 1-seeded Berdych battled fourth-seeded Gilles Simon for nearly 3 hours before claiming a 6-7 (5-7), 6-2, 7-5 decision. Raonic, seeded third, defeated defending champion and No. 2-seed Richard Gasquet 3-6, 6-5, 6-4.
Sunday's final will be only the second meeting between Berdych and Raonic. Raonic won in the three sets last year in Cincinnati in the other.
Berdych is 8-10 in ATP title matches, having lost at Marseille and Dubai this year. His most recent tournament win was last October in Sweden. Raonic, who won the ATP's stop at San Jose, Calif., earlier this year, is 4-4 in finals.
Berdych had six breaks against Simon, with the final one putting him one game from the win. Simon jumped out to a 0-40 lead in that game but Berdych answered with the next five points for the match.
Raonic, who had 23 aces, dropped his serve just once Saturday. Gasquet won a solid 78 percent of the points on serve but Raonic managed the only breaks of the second and third sets to claim the victory.
The Thailand Open championship is worth $102,450 to Sunday's winner with the runner-up earning $54,000. The spots in the semifinals were worth $29,230 to both Gasquet and Simon.