This was the fifth meeting between the pair, and big-hitting Latvian Ostapenko had won on each previous occasion.
Their last two matches had been close but Ostapenko was completely in charge in the semi-final in Doha on Friday, racing to a 6-3 6-1 victory in just an hour and eight minutes.
She'll meet Amanda Anisimova in the final after the American later defeated Russian Ekaterina Alexandrova 6-3 6-3 in one hour and 30 minutes to reach her second WTA 1000 final.
The former French Open champion Ostapenko had one of jher spectacular days, striking 31 winners compared to only eight for Swiatek, who slammed her racquet to the ground in frustration after going 3-0 down in the second set.
It is the most one-sided defeat the world No.2, who was on a 15-match winning streak at the tournament, has suffered since a loss to Elena Rybakina at Indian Wells two years ago.
"I feel like this court has a special energy," said Ostapenko in her on-court interview.
"I was pretty confident that I would beat her because we've played a lot of matches and I kind of know how to play against her.
"I'm really happy with the way I'm handling my emotions this week. I'm just so happy to be in the final."
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