Garcia defeated Swiatek in three sets on Saturday (AEST), ending the world No.1's 18-match winning streak on clay.
Paolini should have provided a far more straightforward task, and so it proved, as Garcia raced through 6-1 6-2 to make the title match.
The No.5 seed will now face first-time WTA Tour finalist Ana Bogdan – a 7-5 7-5 victor against Kateryna Baindl – in that Warsaw decider.
Garcia will hope for better conditions for the showpiece, with rain having added another factor on Saturday, when the in-form French star was still recovering from stopping Swiatek.
"It's been a challenging week, especially today, with the big win yesterday, only a couple of hours to recover and be ready," Garcia explained.
"Conditions were very difficult, a lot of rain. I'm just very happy with the way I played, and I stayed very focused on the present, and it paid off."
At the Prague Open, Anastasia Potapova will face Marie Bouzkova in the final, the No.7 seed playing the No.8 seed.
Potapova had it largely her own way against Wang Qiang, who succumbed to a second-set bagel in going down 6-3 6-0, while Bouzkova also won in two but needed a tie-break in the opener against Linda Noskova, progressing 7-6 (7-4) 6-3.
Potapova faces a busy Monday (AEST), as she had already advanced to the doubles final alongside partner Yana Sizikova.