He eased away to give trainer Jean-Claude Rouget his fifth win in the Prix du Jockey Club and owner the Aga Khan his eighth stretching back to Charlottesville in 1960.
Vadeni impressed the bookmakers who slashed his price for October’s Prix de l’Arc de Triomphe to 8/1.
Two English runners filled the minor positions, Bodegon trained by James Ferguson was second and third-placed Modern Games put up a gallant performance in trying to add the Derby to his French 2000 Guineas crown.
Soumillon said he had never doubted the outcome once they entered the finishing straight.
“I was coasting behind the leaders,” said Soumillon.
“I was in a much happier frame of mind when I saw the redraw (the race had to have a second draw after several glitches in the first one).
“I really wanted to ride another Jockey Club winner for the Aga Khan as it had been a long time since the last one (Darsi in 2006) and sadly he is not here.
“However, I am so happy to do so as I owe him everything.
“This is also terrific as it is a late birthday present!”
Rouget for his part said once Vadeni hit the front it was time to put down the binoculars for his rivals.
“That was a procession,” he beamed.
“I only thought this horse was good, no more than that. But this was no contest.”
For Ferguson finishing second was like winning.
“I’ve never been so happy to come second,” said Ferguson.
“All credit to the winner, he’s a fantastic racehorse and won very well.
“We’ve beaten everyone else, he wears his heart on his sleeve and was given a good ride. I’m looking forward to seeing what he can do in the future.”
Such was the pace set up front by Modern Games the fancied runners such as Onesto and another Rouget runner Al Hakeen whose jockeys decided to sit at the back were caught out.
Both of them finished like trains but it was way too late as Al Hakeen finished fourth and Onesto fifth.