The 3/1 favourite for the Group One under an inspired Frankie Dettori, the John and Thady Gosden-trained bay travelled in mid-division before breaking clear from the rest two furlongs from home in the mile-and-a-half showpiece.
From there the Oaks runner-up, who had disappointed when last of six in the King George VI And Queen Elizabeth Stakes, was unreachable, triumphing by three lengths from Ger Lyons' 50/1 chance Thunder Kiss.
"It would have been heartbreaking not to win a Group One with this filly this year after what happened at Epsom in the Oaks," said Dettori.
"She's won a Group One, I'm delighted and she will stay in training next year.
"Nothing went right at Epsom, then for some reason she ran no race in the King George. John and the owners decided to give her a break. I've been riding her last couple of mornings and she has been given me the 'wow' factor again.
"It's an amazing job the team has done. After four months to be pitched into a Group One and do what she did is amazing."
Gosden senior said: "The boys are saying the ground is very soft, they can't find the good to soft, but she went through it all right.
"I have owners who've let me be patient, they've let me give her all the time she needed.
"I'll never work out the King George as long as I live, full marks to Pyledriver as he let them go mad up front. I don't know what they all did, it was as if someone said 'last one to Swinley Bottom is a sissy' or something.
"Anyway, we gave her a lot of time off, gave her every chance to come back and the whole team have done a great job to get her confidence back mainly, she finished tailed off last so it's where she was mentally. She was unlucky in the Oaks so thank god we won a Group One this year.
"I had everything right in her work and Frankie wanted to ride her, but I didn't know about the ground. She's a big girl but she hasn't strengthened into her frame, she's still quite light, so it was if she handled it. Mind you, she was so wide she was probably on fresh ground.
"She stays in training. I don't think she'll go to the Breeders' Cup.
"The aim next year will be the King George and the Arc. She's won her Group One and we'll let her have a holiday now."
Lyons was rightly proud of Thunder Kiss' effort.
He said: "It was a great run. Fabulous. It was worth coming. She has retired now, so her last run was her best run ever. Conditions suited. There was ease in the ground, a mile and a half, a good pace.
"We thought we'd be in the mix somewhere, because a strong-run mile and a half, the better the race, the better she runs.
"Maybe we should have run her in more Group Ones. She has been a star for us and very consistent. We will miss her and finding a replacement for her will be hard, but we'll try."
Another Irish raider, Willie McCreery's Insinuendo, was third at 80-1.
McCreery said: "Take out her last run, she has had three great runs this year. That is why she was 80-1. She has to settle and she settled beautifully in the race.
"We thought if she was a bit closer, we might have been closer again, but the first thing was to get her settled and that's why she came home so well.
"She is in the sales, but we might take in another race. This was originally the last race, but she has run so well, we will see. She is lightly raced. She stayed on brilliantly."