The duo defeated Spain's Marcel Granollers and Argentina's Horacio Zeballos 6-3, 7-5 in the semifinals of the clay-court tournament in the Italian capital on Friday.
Zieliński and Nys will face the Dutch duo of Robin Haase and Botic van de Zandschulp in the championship match on Sunday.
Zieliński and Nys in January reached the final of the Australian Open men's doubles in Melbourne, where they lost 4-6, 6-7 to home favourites Rinky Hijikata and Jason Kubler.
Playing in the Grand Slam final in Australia was the biggest success for the 26-year-old Pole in his career so far.
Last year, Zieliński reached the quarterfinals of the US Open with Nys.
Jan Zieliński and Hugo Nys. Photo: PAP/Marcin Cholewiński
The Polish player has two doubles titles to his name, both earned at the Metz Open, with countryman Hubert Hurkacz in 2021 and with Nys last year.
The 2023 Italian Open runs until Sunday.
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Source: IAR, PAP