After taking out tournaments in Doha and Indian Wells this year, the 20-year-old's undefeated streak now moves to 15 in a row.
Kvitova largely stayed in points in the opening exchanges and held a higher first-serve rate than Swiatek, but indicative of the form the Polish star is currently in, she played with clarity and did not hesitate when opportunities presented.
Along with winning six of eight points on Kvitova's second serve in the first set, the soon-to-be world number one converted on her sole chance at break point, claiming the crucial break in the sixth game before closing the opening set out.
After a tough service hold in the fourth game and four initial chances at break point in the second set, Swiatek made it count on her fifth attempt, spectacularly managing to move the 28th seed around the court and turn defence into attack.
Seeing the finish line, the Polish second seed grew increasingly assertive in both serve and shot selection to both secure the break and see out the match, even claiming a second break for a punctuation mark.
Swiatek will face Jessica Pegula, who is also through to the semi-finals after Paula Badosa retired from their matchup due to a viral illness.
Pegula was leading 4-1 after only 18 minutes of play when Badosa retired, having won four straight games after initially dropping her serve.
The 28-year-old has now won her last two matches in Miami via retirement after she advanced past Anhelina Kalinina in the fourth round, winning the first set 6-0.
If Pegula defeats Swiatek in the semi-final, it would make for her maiden WTA 1000 final appearance.
Navarro, who had never made it past the first round in her previous appearances at New York, put on an impressive display to win in straight sets against Paula Badosa.
The American found herself 5-1 down in the second set, only to win the next six games in a row to reach her maiden grand slam semi-final.
She also became the second American player since 2000 to make their first grand slam women's singles semi-final at the US Open, after Jennifer Brady did so in 2020.
But waiting in the next round is last year's runner-up, Sabalenka, or the recently crowned Olympic champion Zheng, a challenge Navarro is not shying away from.
"I've played both of them a couple of times,” said Navarro. “They are great players, I think we will have a great battle. But I'll be up for the challenge of either of them.
"Both big servers, big hitters and I think they will come aggressively at me whichever one it is - but yeah I'll be ready."
Navarro had only won one match at the main stage of a grand slam before this year, but has got better and better throughout her breakout year of 2024.
She reached the third round of the Australian Open, the last 16 at the French Open, the quarter-finals at Wimbledon and now the semi-finals of her home slam.
"After I got it back to 5-2, I had a bit of an inkling that it might be two sets," added Navarro.
"I just wanted to stay really tough and stick in there and even if I did lose the second set, I wanted to set the tone for the third set.
"Just really happy with my performance today. Crazy to be moving on to the semi-finals. US Open baby."
Navarro, who had never made it past the first round in her previous appearances at New York, put on an impressive display to win in straight sets against Paula Badosa.
The American found herself 5-1 down in the second set, only to win the next six games in a row to reach her maiden grand slam semi-final.
She also became the second American player since 2000 to make their first grand slam women's singles semi-final at the US Open, after Jennifer Brady did so in 2020.
But waiting in the next round is last year's runner-up, Sabalenka, or the recently crowned Olympic champion Zheng, a challenge Navarro is not shying away from.
"I've played both of them a couple of times,” said Navarro. “They are great players, I think we will have a great battle. But I'll be up for the challenge of either of them.
"Both big servers, big hitters and I think they will come aggressively at me whichever one it is - but yeah I'll be ready."
Navarro had only won one match at the main stage of a grand slam before this year, but has got better and better throughout her breakout year of 2024.
She reached the third round of the Australian Open, the last 16 at the French Open, the quarter-finals at Wimbledon and now the semi-finals of her home slam.
"After I got it back to 5-2, I had a bit of an inkling that it might be two sets," added Navarro.
"I just wanted to stay really tough and stick in there and even if I did lose the second set, I wanted to set the tone for the third set.
"Just really happy with my performance today. Crazy to be moving on to the semi-finals. US Open baby."
The American looked to be heading to a decider but put together an incredible run to win 6-2 7-5 on Arthur Ashe Stadium in 74 minutes.
Navarro had never made it past the first round in her previous appearances at Flushing Meadows but has followed up her Wimbledon quarter-final run with another impressive showing.
Badosa, who has been on a recent resurgence with her title in Washington last month, struggled to gain a foothold, losing her serve twice in the first set and failing to get a break in the penultimate game.
She looked back to her usual self in the second though, racing into a commanding 5-1 lead, only to see it slip away from her.
Buoyed by her home crowd, Navarro won the next six games in a row to set up a meeting with either Qinwen Zheng or Aryna Sabalenka in the next round.
Data Debrief: Breaking new ground
It has already been quite the year for Navarro, winning her first WTA Tour title in Hobart in January before reaching her first grand slam quarter-final in Wimbledon.
But her performance in her home tournament has the potential to be the pick of the year. Into her first major semis, she is also now guaranteed a top-10 debut next week.
Navarro is the sixth player in the last 40 years to make the women's singles semi-finals at the US Open without a win at the event entering the tournament, after Steffi Graf (1985), Venus Williams (1997), Yanana Wickmayer (2009), Bianca Andreescu (2019) & Emma Raducanu (2021).
Williams announced her participation at Wimbledon after receiving a wildcard last week, having been absent since a first-round retirement against Aliaksandra Sasnovich at The All England Club last year.
The American great will team up with Ons Jabeur to play doubles at Eastbourne over the coming days as the 40-year-old prepares for her Wimbledon return.
But Pliskova, who lost last year's Wimbledon final to Ashleigh Barty, says Williams could struggle to match her previous exploits after coming back from a long-term leg injury.
"I don't know how long it has been since she has played. Has it been a year? It is a long time, and she is not the youngest any more, so I suppose the body also takes some time to get back into shape," Pliskova said ahead of her own campaign at Eastbourne.
"Playing matches at tournaments is still very different to just practising and from what I understand, she is not playing [singles] here, she is just playing doubles.
"I think it will be difficult, super difficult for her, no matter what kind of player she is because this is a thing where you still need some time.
"But of course, she is an amazing player, she achieved so much and still a number of players will be super scared to play her. This is her advantage but let's see the level. I cannot really say."
Pliskova has won two of her three grand slam meetings with Williams, eliminating her at the quarter-final stage at the 2019 Australian Open and in the final four at the 2016 US Open.
While the world number seven may have cast doubt upon Williams' chances, Paula Badosa is not keen on the prospect of facing the 23-time major champion on the grass.
"I think it surprised everyone but it's very good to have her back. It really amazes me how she has all this hunger for the game," the world number four said.
"It is a great inspiration. It is nice to have her back and I hope she can be back for much more time because I think she does very good for tennis.
"But the other side, of course I don't want to play against her! I hope the draw goes for another player because no one wants to play against Serena and [even] less on grass. Let's pray for that!"
