Kazakhstan's Rybakina advanced to the quarter-finals of the season's opening Grand Slam for the first time with an impressive display against the misfiring Pole.
"It was a really tough match and I really respect Iga because of the strike she has and the Grand Slams," said Rybakina.
"She's a young player and she plays really well. Today I think was serving also good, just struggling on one side.
"Then in the important moments I played really well and it made a difference."
Rybakina, seeded 22nd, will face Latvia's Jelena Ostapenko in the quarter-finals.
Swiatek, the reigning French Open and US Open champion, got off to a rough start, surrendering her opening service game after receiving a warning from the chair umpire over the time she took for her pre-match preparations.
She fought back to level the scores by the fourth game but Rybakina would break again, clinically punishing the Pole's second serve to take the opening set.
Swiatek looked to have recovered after she rattled off three straight games at the start of the second set behind a more aggressive forehand, only for Rybakina to haul herself level with another break of serve.
The Russia-born right-hander broke Swiatek again at 4-4 in the second set before holding her own serve in convincing fashion to close out the match.
Rybakina's win sees her progress to a third Grand Slam quarter-final having also reached the last eight at the 2021 French Open before winning Wimbledon last year.
Swiatek said the pressure had been building over the last two weeks and she had been going into matches hoping not to lose rather than wanting to win.
"I felt today that I don't have that much to take from myself to fight even more. I felt I took a step back in terms of how I approach these tournaments and I maybe wanted it a little bit too hard," Swiatek told reporters.
"So I'm going to try to chill out a bit more. That's all.
"I felt the pressure and I felt that I don't want to lose instead of I want to win. So that's a base of what I should focus on in next couple of weeks."
Swiatek went on a 37-match winning streak last year before losing in the third round at Wimbledon. She bounced back to win at Flushing Meadows but heading into Melbourne Park the Pole said she wasted too much energy worrying.
"Before the US Open I was actually able to kind of let it go because I played pretty bad in Toronto and Cincinnati, and that helped me to reset and just start the U.S. Open without actually expecting much from myself," she added.
"Here was different, so I'm not connecting the US Open with the streak at all. I'm not comparing this situation to my Wimbledon loss."
Swiatek said she would learn from the defeat.
"Usually if my whole experience at the tournament was tougher and then it comes to an end, I'm able to not focus about the fact that I lost the match but about the overall performance and what's going on with me," she said.
"So this time, I think it's going to be motivating for me and I'm sure I'm going to play next tournaments with something to focus on, something to work on, and I'm going to go forward."