“You’re too sexy for me.” Thus did Rod Stewart crush Alessandro Ristori’s dreams of a duet. They met backstage at Annabel’s nightclub, in London, where the Italian cabaret singer was a regular entertainer. Despite their three-decade age difference, it’s easy to see a kinship between the two singers. Ristori, whose repertoire relies on torch songs and lounge classics, dresses like Stewart in his heyday: bell-bottoms, open shirts, and double-breasted blazers, heavy on the polyester.

Stewart, though, is just one source of inspiration for Ristori. Think of the 41-year-old as an endearing mash-up of Julio Iglesias and late-era Elvis with a winking whiff of Austin Powers. His too-much-is-never-enough retro style has turned Ristori into a de facto mascot for the fashion world. His nickname is “Gucci Guy,” thanks to all the free clothes he’s received from Gucci C.E.O. Marco Bizzarri. Ristori is also the entertainer of choice for playboy Flavio Briatore, whose Twiga club and restaurant, in Forte dei Marmi, is one of his residencies. Accompanied by the Portofinos, his backing band, Ristori was also the wedding singer at the reception of Charlotte Casiraghi last summer. Call him kitsch, perhaps, but never inauthentic. “It’s not a project—that’s the secret,” he says, in Italian-accented English. “You’re believable only if you’re the same person onstage and off—and I am.”