Top seed Swiatek will meet Belarusian powerhouse Aryna Sabalenka, while in-form Frenchwoman Caroline Garcia battles tough Tunisian Ons Jabeur on Thursday with trips to the final on the line.
"It feels like we all earned it," Swiatek said after her straight-sets quarter-final win over American Jessica Pegula.
"Sometimes the semi-finals players are all a surprise. Right now we're pretty solid. So I'm happy about that."
No one is surprised to see the Swiatek in the mix. The Pole went on a blistering 37-match winning streak earlier this year before cooling off ahead of the New York Grand Slam.
Despite struggling in the earlier rounds she raised her game late on Wednesday, whipping forehands and playing excellent defence to see off Pegula.
Standing in Swiatek's way is sixth seed Sabalenka, who showed her mettle by storming back from a set and 5-1 down against Kaia Kanepi in the second round, saving two match points along the way.
"She's a tough opponent, but I'll do my best to make her work as much as I can," Sabalenka said of Swiatek, who holds a 3-1 lead in their head-to-head meetings.
Garcia, seeded 12th, is enjoying a career renaissance and playing with confidence bordering on swagger after cruising to the semis without dropping a set.
Since coming back from a foot injury in May, the 28-year-old has won three events on three different surfaces - on clay in Warsaw, where Swiatek, grass in Bad Homburg, and the hardcourts at the Cincinnati Open.
Jabeur got the better of Garcia several times during their junior days, something the Frenchwoman wants to put right.
"A few times she stopped me on my way to get a Slams in juniors," Garcia said after beating Coco Gauff in the quarters.
"It's fun to see her again in semi-final in US Open. It's a great challenge for my game, for me. I'm really looking forward to it."
Jabeur said she expects a tough battle.
"I'm happy for her that she's back where she belongs," she added.
"Whoever is going to be able to impose her game is going to be in better form. So I will try to play my game. I will try to be me."