The 24-year-old defeated Russia's Diana Shnaider 7-6, 6-4 in the women's singles semifinals at Roland Garros in Paris on Thursday.
"It's like a dream, honestly," Chwalińska said in her on-court interview. "I don't know what's going on. I don't know what to say. I'm just very happy."
Chwalińska had never previously reached the French Open main draw before advancing through qualifying this year.
She now has the opportunity to become only the second qualifier to win a Grand Slam singles title, following Britain's Emma Raducanu, who captured the 2021 US Open crown.
Chwalińska will face Russian teenager Mirra Andreeva in the championship match on Saturday.
Marcin Matuszewski reports.
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