The Ukrainian, who had beaten Ferrer only once in seven previous matches, won handily on the outdoor clay 6-4, 6-4.
"I always have these type matches with him, and usually at the end he would beat me," Dolgopolov said. "I knew I'd have to make those shots. If you don't win the points against him, he takes it away. I'm really happy I didn't get tight and give away a lot of shots."
Dolgopolov has won two previous ATP titles, but this will be his first of the season. Ferrer won the Copa Claro last weekend in Buenos Aires, his third consecutive title in that clay-court event. He has 21 ATP titles.
In the combined, ATP-WTA event, top-seeded Klara Zakopalova of the Czech Republic and fifth-seeded Kurumi Nara of Japan will face off in the women's final.
Zakopalova defeated local hope Teliana Pereira 6-2, 6-1, and Nara won over Nastassja Burnett of Italy 6-4, 3-6, 6-2.
Zakopalova will be aiming for her third WTA singles title. She won two in 2004, and since then has been a losing finalist 11 times.
This will be Nara's first WTA singles final.
"I'm very surprised because it's on a clay court," said Nara, a university student who prefers hard courts.