Vinci, seeded seventh, topped fifth-seeded Dominika Cibulkova 7-5, 6-1 and Dokic advanced after she built a 6-4, 2-0 lead before qualifier Romina Oprandi retired.
Vinci piled up seven breaks and won 59 percent of the points off Cibulkova's serve. Cibulkova also had seven double faults.
Cibulkova earlier finished off a quarterfinal match against second-seeded Svetlana Kuznetsova. Cibulkova was ahead 2-0 in the third set Thursday when rains caused a stoppage of play. Friday she took the third set 6-2 to advance to the match versus Vinci.
Dokic cashed in all three of her break-point chances in building her advantage over Oprandi.
Vinci and Dokic have never played each other. Vinci will be looking for her fifth WTA title and second this year. She broke an eight-match losing streak in winning the championship at Barcelona this year. Dokic has six championships to her credit, including a win at Kuala Lumpur in 2011.
Saturday UNICEF Open winner will take home $37,000 and the runner-up earns $19,000. Cibulkova and Oprandi collected $10,400 each as semifinalists.