The result means the Pole will contest her first grand slam quarterfinal when she faces Italy’s Martina Trevisan on Tuesday.
“I am, I think, stunned,” Swiatek told reports after her victory.
“I was thinking about it (last year’s game against Halep), because as I said, it gave me, it was like a huge lesson for me,” she said. “I knew that I can play differently and I can finally show my best tennis.
“So I was thinking about it, but more in a positive way because I was thinking of a whole process that I’ve made and progress,” Swiatek said. “So, yeah, I mean it wasn’t like I was scared because of that, because I lost in 45 minutes last year. It was kind of motivating for me just to play better.”
Victory for the world No. 54 now throws the women’s draw wide open.
With pre-tournament favorite Halep knocked out, the focus will now turn to the likes of world No. 5 Elina Svitolina, Australian Open champion Sofia Kenin and two-time grand slam champion Petra Kvitova as the top-ranked players left in the draw.
It also means this year’s French Open will crown a new women’s champion next Sunday.
“She played unbelievable today and she was everywhere and she hit all the balls in very strong, very powerful,” said Halep of Swiatek. “It was a little bit cold and I couldn’t be at my best, but, yeah, she played really well … it was her match today.”
He next plays 19-year-old Jannik Sinner, who became the first person since Nadal in 2005 to reach the French Open quarterfinals on debut on Sunday.
Sinner, also the youngest player to reach the last eight of a grand slam in 14 years, upset US Open runner-up Alexander Zverev 6-3 6-3 4-6 6-3.
On the other side of the draw, Novak Djokovic remains untroubled as he chases his 18th major title. He defeated Daniel Galan 6-0 6-3 6-2 on Saturday.