The two protagonists pulled away from Aidan O'Brien's odds-on market leader Snowfall, who had to settle for a third-place finish.
Eshaada (16-1) had not raced since finishing last of seven behind the Aidan O'Brien-trained favourite in the Yorkshire Oaks in August - but she bounced back to take the Group One honours for trainer Roger Varian and jockey Jim Crowley.
Mystery Angel and La Joconde shared the duties up front before the latter went on at halfway. Ryan Moore had Snowfall tucked away in sixth place and though she made ground in the straight the spark she showed when winning the Oaks at Epsom and the Curragh was missing.
There was little between the first two as they battled it out in the closing stages, with Eshaada getting the verdict by a shot head from Albaflora and Snowfall three and a half lengths away.
Varian said: "Her only poor performance was at York and the Ribblesdale form had worked out very well with the winner (Loving Dream) winning the Prix de Royallieu two weeks ago at ParisLongchamp.
"The ground was tight at York and it's a funny place. Maybe she needs cut in the ground.
"Coming here today she had track form and has always looked a class filly, so I thought she was a touch overpriced beforehand.
"We were very happy with her condition and everything went right during the race. She always had a good position and kicked in the straight. She had to be really tough inside the final two furlongs, but she stuck her neck out and was really game.
"I should think a discussion will be had with the team at Shadwell (regarding the future). We'd love to have her around for another year, (but) that won't be my decision.
"She's a big, scopey filly who is still lightly-raced and you would think her best days are perhaps still ahead of her."
O'Brien said of Snowfall: "She ran an OK race, obviously you would be disappointed she didn't win. She's had plenty of racing, it was a steadily enough run race and they quickened and she followed them, but she just didn't get to them.
"Ryan said he would have preferred the pace to be a bit stronger early. Snowfall was slow away and didn't want to come out and around them. There you go - that's the way it is.
"We haven't said anything really (about next year). We'll see how she is, but that is probably it this year."