World number one Swiatek dominated Italian 12th seed Paolini, a first-time Grand Slam finalist, needing just 68 minutes to capture a fourth crown in five years in Paris.
Swiatek has now won all five Grand Slam finals she has contested. Her other victory came at the 2022 US Open.
She is the fourth woman in the Open era to lift the Coupe Suzanne Lenglen four times - after Justine Henin, Chris Evert and Steffi Graf.
"It's amazing to be here. I love this place. I wait every year to come back," said Swiatek, who clicked into gear after saving a match point against Naomi Osaka in the second round.
"I was almost out of the tournament," she said. "I also needed to believe this one is going to be possible, it's been a really emotional tournament."
Swiatek becomes only the third woman to win the tournament three years running. Henin, in 2005-07, was the last to do so. Monica Seles also achieved the feat as a teenager at the start of the 1990s.
At 23, her four Roland Garros titles is the same number Rafael Nadal, the record 14-time champion, had at the same age.
For the 28-year-old Paolini, it was a sorry conclusion, at least in singles, to an otherwise brilliant fortnight in the French capital.
The world number 15 had won a total of four matches in 16 Grand Slam appearances before advancing to the fourth round of the Australian Open in January.
While she fell short of emulating compatriot Francesca Schiavone, who won the 2010 French Open, Paolini could yet finish on a winning note with her and doubles partner Sara Errani through to Sunday's final.
"I have to say congratulations to you, Iga," said Paolini. "I think to play you here is the toughest challenge in this sport."
Paolini's transformation this season into a player capable of challenging for the biggest prizes stemmed in part from quashing the mindset she needed "a miracle" to beat the best in the sport.
Yet the odds were heavily stacked against her going into the final, with Swiatek unbeaten at Roland Garros since a 2021 quarter-final loss to Maria Sakkari.
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Swiatek takes charge
Riding a 20-match winning streak in Paris, and a winner of 18 straight matches this year after titles in Madrid and Rome, Swiatek quickly set about her business.
She powered an ace to hold in the opening game and had Paolini backpedalling down break point, but the Italian ground out a gutsy hold and then broke Swiatek when the Pole flayed a forehand long.
That triggered a searing riposte from Swiatek, who broke to love to get back on serve and then surged 4-2 in front after Paolini coughed up a costly double-fault.
Swiatek had her opponent constantly scurrying around the court and the errors began to stack up for Paolini, who conceded the first set with a weak groundstroke into the net.
With Swiatek firmly in the ascendancy, Paolini looked lost for answers as the top seed oozed confidence and repeatedly took control of the rallies.
Had it not been for an astonishing recovery against Naomi Osaka in the second round when she saved a match point, Swiatek would have suffered her earliest Grand Slam exit at the French Open.
Instead, that fright served to ignite her title aspirations, reigning Wimbledon and US Open champions - Marketa Vondrousova and Coco Gauff - powerless to stop the Swiatek offensive.
Swiatek had difficulty putting away Karolina Muchova last year when heavily fancied, but there was no such trouble 12 months on as the Pole dismantled Paolini to underline her burgeoning status as the 'Queen of clay'.
The three games won by Paolini were the fewest in the final here since Henin obliterated Ana Ivanovic 6-1, 6-2 in 2007, which also coincided with the Belgian's fourth Roland Garros title in five years.