The 26-year-old Pole, who is ranked world No. 57 by the Women's Tennis Association (WTA), defeated home favourite Laura Samson, who retired in the third set due to an injury, trailing 6-3, 0-6, 2-4 in their semifinal clash on Thursday.
Fręch will play 48th-ranked countrywoman Magda Linette or the Czech Republic's top-seeded Linda Nosková in the championship match on Friday, her first career WTA final.
Linette and Nosková were set to face off later on Thursday.
The 2024 Prague Open, an outdoor clay-court tournament, runs until Friday.
Meanwhile, Poland's Iga Świątek, the world No. 1 in women's tennis, is set to compete in the Olympic tennis tournament in Paris.
Świątek will face Romania's Irina-Camelia Begu in the first round of the women's singles at the Roland Garros Stadium, the very venue where the Polish star won her fourth French Open title last month.
(gs)
Source: IAR, PAP