He said of Rykiel, whose relaxed striped knitwear was seen as a shift away from more formal suits: "She invented not just a style but an attitude, a way of living and being, and offered a freedom of movement."
Jean-Marc Loubier, chairman and chief executive of First Heritage Brands, the parent company of the Sonia Rykiel label, said: "It is a sad day but Sonia Rykiel leaves behind her an extraordinary legacy."
He added that she had "helped women and society evolve."
Rykiel was born Sonia Flis in Paris in May 1930, to a Romanian father and Russian mother.
She started her career as a window dresser in 1948, with her first foray into design being when she knitted herself maternity dresses after marrying Sam Rykiel, the owner of a Paris boutique.
Rykiel made her breakthrough in 1962 with the so-called poor boy sweater, which had long sleeves and a fitted shape.
Elle magazine then featured teenage pop star Francoise Hardy wearing a red and pink striped Rykiel sweater on its cover in December 1963.
Brigitte Bardot was later photographed in a Rykiel creation, with Audrey Hepburn among her other famous fans.
Rykiel opened her first ready-to-wear store on Paris's Left Bank in 1968 and her fashion empire went on to include menswear, children's clothing, accessories and perfumes.
According to her website, Rykiel "urged women to be eccentric, seductive, mysterious, and to create their own style".
During her career she developed new techniques like inside-out stitching and no-hem finishings, with other star pieces including embroidered knitted tops and rhinestone-studded berets.
Rykiel wrote several novels and also featured in 1994 film Pret-a-Porter, Robert Altman's satirical take on the fashion industry.
In a 2005 interview, she said she had been plagued by doubt in her early career.
"When I started in fashion, for the first 10 years, I said to myself every day, 'I'm going to quit tomorrow,'" she told Le Nouvel Observateur.
"People are going to figure out that I don't know anything. I always thought I'd be discredited in the end."