Swiatek will face defending champion Aryna Sabalenka in a rematch of last year's final after the Belarusian rallied from a set down to edge fourth-seed Elena Rybakina 1-6 7-5 7-6 (7-5) on Thursday.
Heading into the contest having won two of their last three meetings, the 22-year-old Swiatek dominated from the start and wrapped up the opening set in just over half an hour against the American 18th seed.
The second set was no different with Keys causing little trouble to Swiatek as the world No.1 broke early and raced into a 5-3 lead before breaking again to secure the win.
"I feel really good," Swiatek said. "I wasn't really thinking about what happened last year. But repeating this result is a great thing.
"I'll have a chance to play a nice match in two days. So it's really exciting. I'm happy overall with the whole tournament."
Swiatek, a four-times grand slam champion, is now the youngest player to reach 10 WTA level finals on clay since Swiss Martina Hingis in 2000.
In the second semi, Rybakina looked on course for an easy victory after taking the first set for the loss of just one game.
But as the 2022 Wimbledon champion was serving for the match, Sabalenka shifted the momentum by breaking the Kazakh's serve and then holding her own to force a decider.
After a thrilling third set the match went to a tiebreak where the two-time grand slam winner prevailed.
"It's definitely going to be a great battle. We're always fighting as hard as we can," Sabalenka said.
"It's always incredible matches. I'm really looking forward to this final. I'm gonna do everything I can to get this win."
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