(CNN) -- Fashion designer Hubert de Givenchy, a pioneer in high-end ready-to-wear clothing and famous for styling Audrey Hepburn's little black dress in "Breakfast at Tiffany's," has died at the age of 91, the House of Givenchy confirmed on Monday via its official Twitter account.
"The House of Givenchy is sad to report the passing of its founder Hubert de Givenchy, a major personality of the world of French Haute Couture and a gentleman who symbolized Parisian chic and elegance for more than half a century. He will be greatly missed," the company announced.
His longtime partner, former haute couture designer Philippe Venet, revealed in a statement to AFP that Givenchy died in his sleep on Saturday.
Givenchy entered the world of fashion in 1944 at the age of 17, training under Parisian designer Jacques Fath.
Before long, he had moved on to designing for several major fashion houses including Robert Piguet, Lucien Lelong and Elsa Schiaparelli.
Givenchy was in his mid-20s when he threw caution to the wind and launched his eponymous label in 1952. He maintained low overhead costs to keep down the prices of his designs.
His first collection -- which championed the concept of separates and featured flawlessly detailed embroidered pieces, chic silk prints and sophisticated ball gowns -- immediately drew international recognition.
From the off, he blazed a trail of innovation in the industry starting with his "Bettina blouse," named for popular French 1950s supermodel Bettina Graziani, which reintroduced tailored shirts into high fashion.
But Givenchy was perhaps best known for his decades-long friendship with his muse Audrey Hepburn, which blossomed while she was filming her 1954 hit "Sabrina."
Givenchy continued to style her outfits for "Breakfast at Tiffany's," "Funny Face" and "How to Steal a Million" and their friendship would endure until Hepburn's death from cancer in 1993.
"It was a kind of marriage," Givenchy told the UK's Daily Telegraph newspaper in 2015. "Little by little, our friendship grew and with it a confidence in each other," he added.
"There (was never) any criticism of the other person, no upsets."
Over the years, the haute couturier became a firm favorite of some of the world's most glamorous and highly admired A-listers.
When Jackie Kennedy accompanied her husband to Paris in 1961, she turned to Givenchy to help dress her.
"It was not the same relationship or friendship that I had with Audrey," the couturier said in 2012 of his work with Kennedy. "The American people felt emotion for Jackie, but they preferred to have an American couturier design her dresses when they came to France for a state visit. Jackie asked for more than 10 or 15 pieces, saying 'I don't know if I can be dressed by a French designer.'"
He continued: "We did all the fittings in secret. Then after the event at Versailles, Jackie sent me a little postcard to tell me that General de Gaulle gave her a very nice compliment. He said, 'Madame, this evening you look like a Parisienne.'"
During his illustrious career, Givenchy also styled the likes of Elizabeth Taylor and Princess Grace of Monaco.
Today, his label continues to be relevant and innovative, remaining incredibly popular with celebrity fans including Beyoncé, Kanye West and Rihanna. Beyoncé's love of the fashion house's style is well-known, with her having worn its creations to the last five Met Galas she attended between 2012 and 2016 (she didn't attend the gala in 2017).
Fashion elite mourn
Givenchy gave up the fashion house in 1988 -- it has been under the ownership of luxury goods group LVMH since then -- with the founder retiring after his final collection in 1995.
On Monday, Bernard Arnault, chairman and CEO of the LVMH Group, issued a statement expressing his sadness at the passing of Givenchy.
"I am deeply saddened by the death of Hubert de Givenchy. He was among those designers who placed Paris firmly at the heart of world fashion post 1950 while creating a unique personality for his own fashion label," Arnault said.
"In both prestigious long dresses and daywear, Hubert de Givenchy has brought together two rare qualities: to be innovative and timeless. I extend my most sincere condolences to his family and to all those who have known him," he continued.
Upon news of the aristocratic designer's death, many used social media to share their condolences.
"Farewell, Hubert de Givenchy, whose work with Audrey Hepburn defined the relationship between designer and muse, but who was also so much more," wrote New York Times fashion critic Vanessa Friedman on Twitter.
Nina García, Elle magazine's editor-in-chief, posted: "RIP Hubert de Givenchy. A true couturier. 'The eternal apprentice' as he liked to call himself. He believed in beauty and he left us a more beautiful world. He dressed stars and created fashion icons like Audrey Hepburn. I hope you can now reunite with your teacher Balenciaga."