Yves Saint-Laurent confirmed Monday that Italian designer Stefano Pilati was quitting but did not name his successor.
"The house will disclose the name of the new creative director in the coming weeks," a company statement said, adding that Pilati would present his last collection for YSL on 5 March.
Pilati "accompanied the revival and respositioning of this great French luxury brand," it added.
Designer Hedi Slimane, whose admirers include rock stars and fashion trade peers, will replace Pilati, industry sources told AFP over the weekend.
Slimane, whose father is Tunisian and mother Italian, is returning to the fashion industry after several years away. He had worked at YSL in the late 1990s as head of the menswear collection.
He made his mark at Christian Dior between 2000 and 2007, where he is generally acknowledged to have revolutionised menswear.
A rock fan and artist, Slimane drove an androgynous look of skinny suits and tight low trousers that found its imitators not just in the fashion world but spread into the rock world that so fascinates him.
Stars Mick Jagger and Pete Doherty have gone on stage in Dior Homme, while designer Jean-Paul Gaultier once said he could not do better than Slimane.
Even the legendary Karl Lagerfeld shed some 45 kilos (90 pounds) to be able to slide into a pencil-thin Slimane suit.