The singer, who called the experience "surreal," got cheers as he weaved, in a long tweed coat, between the dinner tables of well-heeled VIPs who included actresses Jada Pinkett-Smith, Willow Smith and Clemence Poesy, as well as singer Vanessa Paradis and South Korean superstar G-Dragon.
Williams was joined on the unusual runway by models such as Cara Delevingne, Georgia May Jagger and Lily-Rose Depp, who wore roses in their hair for the exuberant collection. The fashion lineup featured shimmering, tight-waisted silhouettes with strong shoulders and rendered in navy and off-white with flashes of red and dazzling gold.
The designs evoked the "Cafe Society" evening dresses once worn at the storied hotel - with glimmering embroideries, sunray pleats and marabou and ostrich feathers.
As ever, the nostalgia was infused with modernity in the form of oversized black bubble jackets and funky, bejeweled necklaces that cascaded down the torso.
The Ritz has a special significance for the fashion house as it's where Coco Chanel used to live.
"It's surreal, as there's so much history artistically. And Chanel is a brand that I respect artistically, so I feel like it makes a lot of sense (to host the show at the hotel)," Williams told The Associated Press.
About his choice of look, he answered simply: "I like pearls."
The mid-season "art et métiers" collection honoring the craftsmanship of the Chanel atelier is held once a year in a special location. In previous years, the Chanel atelier has travelled to Rome, Salzburg, Dallas, Edinburgh, Mumbai and New York.
This year, Chanel designer Karl Lagerfeld said he decided to bring it home to Paris in a show of support for the city that's seen tourism decline after a series of deadly extremist attacks.
"Paris has such a bad reputation with the Paris bashing all over the world ... that I thought it would be fun," Lagerfeld said.
The one item from the show the famed couturier did not share enthusiasm for were the luxury pastries the dinner guests ate along with tea and "Belle Epoque" champagne.
"I don't eat this kind of stuff," said Lagerfeld, who famously lost 92 pounds in 13 months over a decade ago.
Thomas Adamson can be followed at Twitter.com/ThomasAdamsonAP
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