The 21-year-old world No 1 from Poland saw off a second set fightback from history-chasing Jabeur to prevail 6-2, 7-6 (7/5) in 1hr 52min at Arthur Ashe Stadium.
The win was Swiatek's second Grand Slam title of 2022 to set alongside her French Open victory in June, which followed her maiden Grand Slam win at Roland Garros in 2020.
Swiatek's victory was her 10th straight win in a final. She is unbeaten in finals since suffering a lone reverse in her first WTA final in Lugano three years ago.
Swiatek collapsed on court in relief after a win that saw her pocket a hefty $2.6 million in prize money.
"I'm really glad it's not in cash," she quipped as she was presented with her winner's cheque for a tournament she entered with low expectations when the season began.
"I wasn't sure if I was on the level yet to win actually a Grand Slam, especially at the US Open where the surface is so fast," she said.
"It's something that I wasn't expecting for sure. It's also like a confirmation for me that the sky is the limit.
"I'm proud, also surprised a little bit, just happy that I was able to do that."
But the loss was another agonising near-miss for Jabeur, who had been bidding to become the first woman from Africa to win a Grand Slam title.
The 28-year-old from Tunis had also been beaten in the final of Wimbledon in July.
"I have nothing to regret because I did everything possible," said Jabeur.
"I'm not someone that's going to give up. I am sure I'm going to be in the final again and I will try my best to win it."