Donna Karan has stepped down as chief designer of the multi-million pound fashion brand she founded more than 30 years ago.

Her decision to leave Donna Karan New York (DKNY) – which is recognised for transforming the working woman’s wardrobe – was announced by the brand on Tuesday.

The award-winning American designer has confirmed that she will now focus on her Urban Zen organisation, which works to improve healthcare and treatment for patients. She set up the organisation after her late husband Stephen Weiss – with whom she co-founded DKNY – was diagnosed with lung cancer and she was disappointed with the treatment he received.

Karan, who has also supported the Beth Israel Medical Centre, said: “I have arrived at a point in my life where I need to spend more time to pursue my Urban Zen commitment to its fullest potential and follow my vision of philanthropy and commerce with a focus on healthcare, education and preservation of cultures.”

Born Donna Ivy Faske to a Jewish family in New York, her father, Gabby, was a menswear tailor before he died when Karan was three years old. Her mother supported the family by working as a saleswoman.

Karan worked for designer Anna Klein before setting up DKNY with her second husband Weiss, an artist.

A spokesman for DKNY said: “Donna Karan is an icon, visionary designer and a passionate philanthropist. She believes in dressing and addressing women. Her impact on American fashion has been extraordinary and she will continue to influence and inspire for years to come."

The company has not announced who will step in as chief designer.