The 19-year-old crushed Sofia Kenin 6-4 6-1 to crown an extraordinary fortnight.
Swiatek, who had dropped only 23 games en route to the final, produced another audacious display as she became the first Polish player to win a Grand Slam singles title.
Only briefly in the first set did Swiatek show any weakness, letting slip a 3-0 lead.
But having edged a tightly-contested opening set she romped to victory, although fourth seed Kenin’s challenge appeared to be hampered by a thigh injury.
Australian Open champion Kenin, herself only 21, needed treatment at 1-2 in the second set and on the resumption Swiatek was utterly ruthless.
She conceded only three more points, sealing the title with an unstoppable forehand, her 25th winner.
Unseeded Swiatek, who was ranked 54th at the start of the tournament, is the youngest woman to win the French Open since Monica Seles in 1992.
She is also the first to do so without dropping a set during the fortnight since Justine Henin in 2007.
After claiming victory she made her way into the stands to celebrate with her family which includes former Olympic rower father Tomasz and her coach Piotr Sierzputowski.
“It was overwhelming for me. Two years ago I won a junior grand slam and now I’m here. It feels like such a short time.
“I’m just overwhelmed,” Swiatek, the lowest-ranked woman to win the French Open since rankings were introduced in 1975, said after returning to the court.
“Another underdog wins a Grand Slam in women’s tennis, it’s crazy.”
It was a sad end to the tournament for Kenin who was unable to find the form that saw her past Petra Kvitova in the semi-finals.
Swiatek began the match on the shady side of the Court Philippe Chatrier court with Kenin in bright sunshine, but it was the Pole’s tennis that illuminated the 84-minute final.
She began as freely as if it was match down at her local club in Warsaw, sprinting into a 3-0 lead.
Kenin, whose tightly-wound and expressive demeanour was a stark contrast to Swiatek’s calm approach, fought back to 3-3 as her backhand began to do some damage.
Swiatek came through a tense service game at 3-3 and in the best passage of play in the final then broke Kenin after another long game.
It was a game in which she saved a game point with a superb drop volley, having chased down a drop shot.
Kenin broke serve with a glorious backhand to trail 5-4 but Swiatek was feasting on the American’s serve and broke for the third time in the set to move to take the opener.
Swiatek dropped serve at the start of the second set but hit back immediately and Kenin’s challenge faded rapidly after she had her left thigh heavily taped.
Logic suggests nerves might have became a factor as glory beckoned but Swiatek bashed winners all over the court to announce herself as the sport’s latest sensation in style.(Reuters/NAN)