The Frenchwoman with a flair for the dramatic knocked out the world No.1 in their third-round contest 6-4 6-2 on Saturday to end Swiatek's incredible 37-match winning run that stretched back to the middle of February.
Swiatek ended up looking a distracted shadow of the woman who has swept all before her since Ash Barty retired from the top of the women's game in March, admitting that she didn't "tank" but did feel confused about what tactics to use as she lost her way in the final stages.
"I tried many things to try to feel better on grass court but it just didn't happen," the 21-year-old said.
"Here, I didn't know what to change. I was confused."
But it was a familiar scenario for the 32-year-old Cornet, who, while perhaps never quite making the best of her talent, has enjoyed some remarkable wins, not least when she beat the then five-times champion Serena Williams at Wimbledon back in 2014.
She'd also caused a major tremor by knocking out 2019 Wimbledon champ Simona Halep in the Australian Open in January.
But this was a quake of a different magnitude as she pummelled the French Open champion to stun the crowd on Court No.1.
But Cornet received a lot of help from the tournament favourite, who's been so uncomfortable on Wimbledon's lawns this week and still looked pretty coltish as she sprayed around 33 unforced errors in an accident-prone 93 minutes.
In contrast, the often unpredictable Cornet was solidity personified, making just seven unforced mistakes as she ended Swiatek's four-month, six-tournament winning streak.
Cornet's win sets up a golden opportunity for Australia's top female player Ajla Tomljanovic, who rallied to beat 2021 French Open champion Barbora Krejcikova 2-6 6-4 6-3.
There were no alarms for Halep, who outclassed Poland's Magdalena Frech 6-4 6-1 win in 66 minutes and will next face No.4 seed Paula Badosa, who knocked out another former winner Petra Kvitova 7-5 7-6 (7-4).
Amanda Anisimova battled back after losing a tight opening set to down Roland Garros runner-up Coco Gauff 6-7 (4-7) 6-2 6-1, describing her win on centre court as "the most special day" of her career.
Harmony Tan's amazing debut Wimbledon, which had been launched with a spectacular victory over Serena Williams, continued as she outplayed Katie Boulter 6-1 6-1 to end the terrific run of Alex de Minaur's British girlfriend.
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