The 409-square-metre store on one of the UK capital's most prestigious shopping streets was designed by Chipperfield with Valentino creative directors Maria Grazia Chiuri and Pierpaolo Piccioli.
It follows the architect's 2014 New York flagship for the brand, which was founded in 1960 by fashion designer Valentino Garavani.
Hard Venetian terrazzo and marble surfaces are paired with soft carpets to create the impression of a grand Italian house.
"The store concept combines old and new in order to generate a kind of palazzo atmosphere, steering away from a pure showroom and promoting a new retail architectural format in place of a more traditional retail boutique structure," said Valentino.
Across the front of the upper floors, a four-by-three grid of windows surrounded by Portland stone displays one mannequin in each opening – akin to ancient Roman buildings where statues were placed in rows of niches.
Terrazzo clads the ground-floor facade, framing a large window and a recessed doorway lined with oak.
Inside, oak is also used for a combined lift and staircase, which forms a focal feature in the centre of the store and connects its four levels.
"This particular kind of elevator is inspired by the ones of the traditional Milanese buildings, built in the void of the staircases, within reduced spaces," Valentino said.
The wood is continued on vitrines and display cases on all floors, contrasting with Carrara marble podiums also used to presented accessories.
Marble wraps around the columns on the ground floor, while more grey terrazzo covers the walls on the upper floors of the store.
Womenswear products including ready-to-wear garments, accessories and fragrances are all carried at the boutique, which also features a VIP area to provide services for customers with appointments.
"The architecture is designed to complement the pieces on display, making use of a range of discreetly opulent materials to focus attention on the collections and evoke a sense of intimacy," said Valentino.
Chipperfield founded his architectural studio in 1985 and has designed buildings including the Museo Jumex in Mexico City, the Hepworth Wakefield gallery in northern England and the Museum Folkwang in Germany.
The architect is working with a variety of fashion brands and department stores to create retail spaces. His recent completed projects include a boutique for Bally in Beverly Hills, and he is currently overhauling London's Selfridges.