Bettencourt's daughter, Francoise Bettencourt Meyers, said in a written statement today that her mother "left peacefully" overnight in Neuilly-sur-Seine.
Liliane Bettencourt was the only child of Eugene Schueller, who founded L'Oreal in the early 20th century.
Forbes magazine estimated her fortune to be worth USD 39.5 billion this year.
L'Oreal Chairman and CEO Jean-Paul Agon expressed "great admiration" for Bettencourt. Agon said she "always looked" after the company and its employees and "she has personally contributed greatly to its success for many years."
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Liliane Bettencourt inherited the L'Oreal fortune upon the death of her father in 1957. When the company went public six years later, she continued to own a majority stake.
As the world's leading beauty company, L'Oreal generated sales amounting to 25.8 billion euros in 2016 and employs 89,300 people worldwide, according to the company.
Bettencourt's name has been involved in a politico- financial scandal known in France as the "Bettencourt Affair", which has wound its way through French courts and newspapers for years.
In 2015, a French court handed Banier a three-year prison sentence on charges of swindling millions of euros from Bettencourt by taking advantage of her weak mental state. The court acquitted a former ally of former President Nicolas Sarkozy in the case.
Sarkozy's former campaign treasurer, Eric Woerth, was acquitted on charges of "abuse of weakness" and taking donations from Bettencourt during the 2007 presidential election campaign.
Bettencourt is survived by her daughter, Francoise, who was born in 1953.