Bago delivered a late burst of pace to steal the Prix de l'Arc de Triomphe at Longchamps and restore his reputation.
The three-year-old's credentials had been doubted after defeats at York and Longchamp this season but there was no mistaking his ability in the Arc.
The Jonathan Pease-trained horse came from the middle of the pack to close down leader Cherry Mix.
Thierry Gillet guided Bago through to push Cherry Mix into second with British raider Ouija Board third.
"It's terrific and I'm so glad he ran," British trainer Jonathan Pease, who has been based in France for nearly 25 years, told BBC Sport.
"He's the best horse I trained. We had slight doubts before the race but they're put to rest now."
Kieren Fallon had made it clear he intended to dictate the pace of the race in Paris as he guided 9-2 favourite North Light into the early lead.
But the Epsom Derby winner quickly became wrapped up in a battle with Japanese raider Tap Dance City.
The pair were oblivious to the challenges from the rest of the field and Andre Fabre's charge Cherry Mix surged into contention.
But Bago, the son of Nashwan and unbeaten as a juvenile, produced his best when it counted finishing fast to notch up the first Arc win for the Niarchos racing family.
North Light finished in fifth spot and trainer Sir Michael Stoute admitted it just was not his day in Paris.
"We were nicely settled in front at one stage but the ground was just too quick for him which concerned us greatly," Stoute told BBC Sport.
"He's come out of it with great credit and hopefully he'll stay on as a four-year-old."
The challenge also failed to materialise from Irish Derby winner Grey Swallow, who had gone into the race heavily backed.
"I'm disappointed," said trainer Dermot Weld. "He was bumped and knocked about a bit.
"We didn't see the real Grey Swallow - he ran a bit flat."