Adian O'Brien claimed the Epsom Oaks the third of the five classics in the British season, with Forever Together. Godolphin's Wild Illusion came second.
She had failed to win any of her three previous starts, most recently finishing runner-up, three-and-a-half lengths behind stablemate Magic Wand in last month's Cheshire Oaks.
On this occasion, Magic Wand, again ridden by Ryan Moore, finished fourth, three lengths behind Bye Bye Baby in third.
"To be honest, I didn't expect her to do it. I had the perfect position the whole way," the winning jockey said of Forever Together. "It all went perfectly.
"When you're riding one of his father Aidan's horses you have a chance, he's an absolute genius. He can do things with horses I don't understand, he brings out massive improvement and I don't know how he does it."
Click Here To Watch Epsom Oaks winner Forever Together Race 2018
Distance:1m 4f 6y (2,420 m), Surface:Turf, Track:Left-handed, Qualification:Three-year-old fillies, Weight 9 st 0 lb, Purse:£450,000
Credit: Pallavi Shevade pallavi.shevade@secretaristworld.com