World number one Swiatek comfortably prevailed against second-ranked Sabalenka in the last major tournament before she defends her French Open crown.
In front of a packed centre court crowd Swiatek won her 12th successive match on clay and became the first woman since Serena Williams in 2013 to win at Madrid and Rome in the same season.
Swiatek will be red-hot favourite to win her fourth title, and third in a row, at Roland Garros which starts later this month after besting Belarusian Sabalenka as she did at the recent Madrid final.
"Another final, another great battle. After Madrid I knew it wasn't going to be easy, it can always go both ways," said Swiatek on court.
"We'll see about that Roland Garros final!"
The Pole took her winning record over Sabalenka to 8-3 in another hugely impressive display from what has been an almost flawless tournament from the four-time Grand Slam champion, who didn't drop a single set on her way to another championship victory.
Saturday's match was less dramatic than Madrid's three-set thriller as Sabalenka, who has won the two most recent Australian Opens, gave herself too much to do.
Swiatek took the opening set in just 36 minutes in a clinical display of tennis against Sabalenka, who has said repeatedly that Rome is her dream tournament to win.
Going into Saturday's final Swiatek had won 97 percent of her matches in which she went one set ahead since the start of 2022 and Sabalenka didn't help her cause by wasting seven break points over two games in the second set.
After Swiatek broke Sabalenka's serve in game seven it was only a matter of time before she closed out the match and championship.
"I would say the first set I didn't play well at all. I wasn't, I don't know, feeling my game well," Sabalenka told reporters.
"In the second set I just tried to stay a little bit more aggressive... I just tried to put her a little bit under pressure.
"I had couple of opportunities to break her serve. Probably if I would take that opportunity, the match would go differently. I didn't use it, so it is how it is."
On Sunday Alexander Zverev bids to win his second Rome title when he faces Nicolas Jarry in the men's final.
Zverev is in his 11th Masters final, equalling Boris Becker's record for the most by a German since the series began in 1990.
