Donna Karan, founder of the eponymous womenswear brand, is quitting her role as chief designer with immediate effect.
Karan, who founded the business in 1984, will retain an advisory role.
In a statement, the American business said Karan’s decision to leave her day-to-day responsibilities was a personal one.
Her designer contributions have become less frequent since 1997 when she left her role as chief executive.
The company went public in 1996, and was acquired by French luxury group LVMH in 2000.
Karan plans to focus her efforts on Urban Zen, a clothing, lifestyle and homewares brand she set up in 2007.
In the UK, Donna Karan stockists include Harrods and Net-a-Porter.