His signature ponytail and dark glasses made him an instantly recognisable figure around the world.
Industry heavyweights, including Italian designer Donatella Versace, issued heartfelt tributes. "Today the world lost a giant among men," said the editor-in-chief of Vogue magazine, Anna Wintour.
Rumours of Lagerfeld's ill health had swirled for several weeks after he missed a number of events - including Chanel's spring/summer show last month.
He died on Tuesday morning after being admitted to hospital the night before, French media report.