The Elusive Quality filly pressed pacesetter Chingun throughout before overtaking that rival more than 400 meters out and scooting clear to a 2 1/2-length triumph as the 19-10 favorite with Racing Post.
Duntle, the 7-1 third wagering choice, and Kenhope battled for the runner-up spot, with the former prevailing by a short head. Chingun faded in the closing stages to finish ninth.
Ridden by William Buick for trainer John Gosden, Elusive Kate was timed in 1:35.20 for the 1,600 meters (about one mile) on turf rated as soft for her second victory from three starts this season. She has won four of five starts at Deauville, including last year's Rothschild by 1 1/4 lengths from dual French classic winner Golden Lilac.
The 4-year-old filly came into the Prix Rothschild after scoring a controversial win July 12 in the Etihad Airways Falmouth Stakes (Eng-I), in which she drifted far left in the final furlong, forcing out runner-up Sky Lantern with her. Sky Lantern's connections argued that Elusive Kate cost their filly the race, but stewards at Newmarket left the result unchanged.
Giofra, who finished third in the Falmouth, finished last of 12 in the Prix Rothschild after being eased in the final 200 meters. She was the 3-1 second favorite.
With her second Prix Rothschild victory Elusive Kate has four top level wins, including the 2011 Total Prix Marcel Boussac-Criterium des Pouliches (Fr-I), a win that propelled her to the Cartier Award as Europe's champion 2-year-old filly.
Overall, she has seven wins, two seconds, and two thirds from 14 career starts.
"She's getting better and better and she's got a very exciting season ahead of her," Buick told Racing Post after the Prix Rothschild. "There was an even pace, we didn't go fast but the ground was pretty testing so the pace was perfect and I was always happy with the position I had. When I looked around I was surprised to see how far clear I was."
Gosden mentioned the Haras de Fresnay-Le-Buffard Prix Jacques Le Marois (Fr-I) August 11 at Deauville and the Coolmore Fusaichi Pegasus Matron Stakes (Ire-I) September 7 at Leopardstown as possible starts for Elusive Kate.
Elusive Kate is among nine grade I or group I winners for Darley's Kentucky-based Elusive Quality, who is the sire of 31 graded or group winners. She is out of the winning Lemon Drop Kid mare Gout De Terroir, a half sister to grade/group I winner and sire Pleasantly Perfect. Second dam Regal State won the 1985 Prix Morny (Fr-I).