The Polish-American duo beat Australia’s Nick Kyrgios and Thanasi Kokkinakis 6-4, 6-3 in the semifinals.
Hurkacz and Isner will take on the Netherlands' Wesley Koolhof and Britain's Neal Skupski in the championship match on Saturday.
In the men's singles, Poland’s Hurkacz has advanced to the Miami Open semifinals, with a 7-6, 6-3 win over Russia's Daniil Medvedev.
Hurkacz, who is defending his men's singles title in Miami, will now face Spaniard Carlos Alcaraz for a place in the final.
In the women's singles, Poland's upcoming world No. 1 Iga Świątek has moved into the final with a 6-2, 7-5 win over home favourite Jessica Pegula.
The 20-year-old Pole is set to play Japan's Naomi Osaka for the title at the Miami Open.
The prestigious annual tournament, which is sometimes referred to as "the fifth Grand Slam," began on March 21 and runs until April 3.
(gs)
Source: IAR, PAP