It took just over an hour for Boulter who won the first set 6-3 and dominated the second 6-1 against the third seed.
The 27-year-old from Leicester dominated on her serve, winning more than 87 per cent of first serve points and allowed just two break points opportunities against her serve, saving both.
Rain stopped play early in the second set, but the delay did nothing to stop Boulter’s momentum as she produced an almost perfect set to secure victory.
Boulter will climb to her career-high WTA ranking after the win as she looks to win her first WTA-500 title in what will be the biggest game of her career so far.
World number two Sabalenka had reached the last 16 without dropping a single set, only losing more than two games in one of six sets of tennis at this year's tournament.
It was more of the same on Court Philippe-Chatrier on Monday, the two-time grand slam winner's power and poise giving world number 22 Navarro few chances to make it a contest.
Sabalenka set the tone by breaking in the very first service game and was a set up within 32 minutes, winning 13 of 14 points behind her first serve in the opener.
Another quick break meant the second set followed a similar pattern, and though Navarro came through a couple of tough service games, she only delayed the inevitable as Sabalenka teed up a last-eight clash with either Varvara Gracheva or Mirra Andreeva.
Data Debrief: No denying Sabalenka
Sabalenka was beaten in her only previous meeting with Navarro at Indian Wells earlier this year, but she gave the American little hope of a repeat on Monday.
The victory made her just the seventh woman to make seven consecutive grand slam quarter-finals this century, after Jennifer Capriati, Lindsay Davenport, Venus Williams and Serena Williams.
The last major where Sabalenka was not involved in the last eight was the 2022 edition of Wimbledon, when Russian and Belarusian players were banned due to the war in Ukraine.
The second seed trailed 4-2 and was a break down in the opening set, but went on to win 11 of the next 13 games to seal a fourth-round clash with either Madison Keys or Emma Navarro.
Sabalenka has dropped just seven games in her opening two matches at Roland-Garros.
Although, it looked like she may lose the opening set when a fortuitous net shot gave Badosa a second break and a 4-2 lead on Court Philippe-Chatrier.
However, she dug deep from 5-3 adrift, winning the last four games to draw first blood.
The reigning Australian Open champion broke her opponent a further two times on the way to a commanding 4-0 advantage in the second.
Badosa did well to save three match points from 0-40 in game six, but the Spaniard could not rescue a fourth as her opponent continued her surge into the second week.
Data Debrief: Sabalenka completes top four in last 16
Following on from her victories when they met in Miami and Stuttgart earlier this season, Sabalenka became the first player to beat Badosa three times at WTA events in a calendar year.
Joining Iga Swiatek, Coco Gauff and Elena Rybakina, this marks the first time since 2013 that the top four seeds are through to the last 16 in the women's singles at Roland-Garros.
The Ukrainian defeated Ana Bogdan 7-5 6-2 on Saturday to reach the last 16 for the sixth time in her career.
Both players struggled on serve, with 11 breaks in total during the match, but it was Svitolina who ultimately emerged triumphant after a back-and-forth contest and a rain delay, firing 28 winners.
Fifteenth seed Svitolina will now hope to halt the Paris charge of fourth seed Rybakina, who is yet to drop a set at the tournament so far. It will be a tough ask, but Svitolina does lead the head-to-head 2-1.
An all-American clash between Madison Keys and Emma Navarro on Court Suzanne-Lenglen was one of the other standout matches.
Navarro had never before reached the fourth round at a major, while Keys was a former semi-finalist at Roland-Garros.
But it was Navarro who claimed a hard-fought victory, getting the better of two tie-breaks to win 7-6 (7-5) 7-6 (7-3) to book a huge clash against second seed Aryna Sabalenka.
Jasmine Paolini is also through to round four after seeing off former US Open champion Bianca Andreescu 6-1 3-6 6-0.
Mirra Andreeva, meanwhile, is the youngest player to reach the French Open last 16 since Nicole Vaidisova in 2006 after beating Peyton Stearns in straight sets.
The 17-year-old raced to a 6-2 6-1 win in only 67 minutes.
Sabalenka and Rybakina had earlier completed routine victories over Paula Badosa and Elise Mertens respectively.
Gauff, who was also comfortably beaten by Navarro at Wimbledon two months ago, fell to a 3-6 6-4 3-6 loss after serving 19 double faults at the Arthur Ashe Stadium.
A bright start from Navarro saw earn a first break in the opening game after two double faults by Gauff in a sign of things to come for the world number three.
Despite a comeback in the second set, Gauff's remaining service games were punctuated by more errors in the third, serving 11 of her total double faults in the final set to hand Navarro the victory.
"I fought really hard today. I just didn't take care of my serve, so that was the biggest difference," Gauff said.
"Mentally and emotionally I gave it my all. Of course, there were things execution-wise, where I wish I could serve better.
"I think if I would did that, it would have been a different story for me in the match."
Navarro will go on to play 26th seed Paula Badosa in the last eight after the Spaniard thrashed China’s Wang Yafan 6-1 6-2 earlier on Sunday.
Data Debrief: Doubles troubles for Gauff
With 19 double faults, Gauff served the equal-most double faults for her career in a single WTA main draw match, serving as many against Martina Trevisan at Roland Garros in 2020.
Navarro is the first American player to defeat the women’s singles defending champion at the US Open since Serena Williams in 2002 against Venus Williams in the final.
She is also now the player with the most hard court WTA quarter-finals in 2024 (seven, surpassing Elena Rybakina).
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).
The Belarusian beat one of the home favourites Emma Navarro in straight sets on Thursday, needing a tie-break to edge past the in-form American.
Sabalenka, who finished as runner-up to Coco Gauff in the tournament last year, won 6-3 7-6 (7-2) in just over 90 minutes on Arthur Ashe Stadium.
After a relatively comfortable first set, Sabalenka looked to be cruising in the second too, until Navarro clawed her way in front after being 5-3 down.
However, the number two seed soon regained her footing to win the tie-break, and she credits the work she has put in on her mindset as the game changer.
"I worked really hard on my mindset on the match," Sabalenka said afterwards. "I think I made really huge improvement on that calmness, on those crucial moments.
"Even if things are not working well for me, I still keep doing the right things, and I'm staying in control. I'm really proud, I'm actually really proud of myself that I was able to get to the point when I'm in control of my emotions."
Data Debrief: Back-to-back
Sabalenka has dropped just one set throughout the US Open this year, and has put herself in the best position to win the competition for the first time.
The 26-year-old is the first woman to reach back-to-back US Open finals since Serena Williams in 2018 and 2019. She has now reached all four hard court grand slam finals in the last two years.
Since the Australian Open's switch from grass in 1988, Sabalenka is just the fifth player to reach the women's singles final at the Australian and US Open in consecutive seasons after Steffi Graf, Monica Seles, Martina Hingis and Victoria Azarenka.
Second seed Gauff entered the match hoping to reach the last eight for the fifth time in her last six grand slam entries, but the US Open champion was stunned by her compatriot.
Nineteenth seed Navarro needed just 76 minutes to wrap up a 6-4 6-3 victory, advancing to the quarter-finals at a major for the first time in her career.
The 23-year-old was broken to love five games into the opener but that setback only spurred her on as she hit back immediately, eventually claiming the second break in the 10th game with a fine passing shot down the line.
Gauff looked nervous at the start of the second set, a double fault and a wayward forehand handing Navarro a break four games in, though the world number two forced her opponent to serve it out after fending off a potential second break.
Navarro failed to convert her first two match points, but it was third time lucky as Gauff crashed a return into the net, sealing the biggest win of Navarro's career.
"I'm just really grateful to be out on Centre Court, where so many legends have played before me, it's a real honour and I just can't wait to play again," Navarro said afterwards.
"It's probably my favourite court I've ever played on. The fans, the atmosphere… just having my family and my team watch me was so special.
"I played really aggressively. Coco's an amazing player, I have respect for her and everything she's done, but I wanted to push back against her and I think I did that."
Data Debrief: Navarro flying the flag
Navarro will now face seventh seed and French Open runner-up Jasmine Paolini for a place in the semi-finals, with Gauff following fellow heavyweights Aryna Sabalenka and Iga Swiatek out of the draw.
She is just the fourth American woman to beat a top-two ranked player at Wimbledon, after both Venus and Serena Williams and Alison Riske.
Osaka was unconvincing in an opening-round win over 53rd-ranked Diane Parry before Navarro, the 19th seed at the All England Club, proved too strong on Centre Court.
Navarro never faced a break point in a one-sided showdown, triumphing 6-4 6-1 in just under an hour against the four-time major champion.
The 23-year-old was offered a glorious opportunity in the first set at 3-3 when Osaka fired four straight unforced errors to hand Navarro the advantage.
A poor volley attempt spelt the end for Osaka in the second set as Navarro cruised home in quick time with 16 winners and only five unforced errors.
Navarro has now reached the third round at all three majors this year as Diana Shnaider, who cruised past 2017 US Open champion Sloane Stephens on the same day, awaits for her next clash in SW19.
Data Debrief: Osaka's grass-court struggles persist
Osaka has now never beaten a top-20 player on grass courts in six attempts, with this another reminder of Navarro's ruthless quality.
This was her first appearance on Wimbledon's famed Centre Court, yet Navarro never looked troubled in a routine triumph.
A tougher test will follow in the third round, however, as Shnaider has downed Navarro twice this year, most recently just last week in the Bad Homburg Open semi-finals en route to winning the tournament.
The seventh seed had never won a WTA main-draw match on grass courts until late last month but progressed into the last four at SW19 after triumphing 6-2 6-1 on Centre Court.
French Open finalist Paolini will fancy her chances of reaching the final as well, with world number 37 Donna Vekic – who overcame Lulu Sun in the quarter-finals – standing in her way of the showpiece.
Having profited from Madison Keys' injury-enforced retirement in the last round, Paolini was slow to get going after Navarro, who stunned Coco Gauff earlier in the competition, broke to seize an early 2-1 lead.
Yet the Italian appeared fuelled by that concession, winning on her opponent's service for three straight games to turn that deficit into a routine first-set triumph in just 27 minutes.
The 23-year-old Navarro struggled to regain her composure in the following set, missing two break-point chances at 1-1 before Paolini followed up by breaking to snatch a 3-1 advantage.
World number seven Paolini hammered home that advantage soon after, cutting through Navarro with ease en route to victory in less than an hour.
Data Debrief: Italian history for Paolini
Paolini is the first Italian women's player to reach the semi-finals at this tournament, having not previously ever won at Wimbledon before this edition.
The 28-year-old is also the oldest player to reach their first semi-finals in two different grand slams during the same season, since Betty Stove in 1977.
