Published Monday, 17 March 2014
L'Wren Scott, pictured with Rolling Stones frontman Mick Jagger. (© Getty)
The rocker had been dating the 49-year-old model and designer since 2001, after splitting from his wife Jerry Hall.
Ms Scott was found in an apartment in Manhattan, New York, on Monday morning.
"A 49-year-old female was found this morning at 10.05am at 200 11th Avenue. She was unconscious," a spokeswoman for New York City Police Department said.
"She was pronounced dead on arrival by the emergency medical services. The investigation is ongoing. We are awaiting medical examiners to determine the cause of death."
It is understood that police are treating the death as suicide.
The fashion designer worked with names such as Thierry Mugler and Karl Lagerfield and as a wardrobe consultant on films including Eyes Wide Shut and Ocean's Thirteen.
Scott, originally called Luann Bambrough, changed her named to launch her modelling career in her teens.
She met Sir Mick, 70, when she worked as a stylist on a photo shoot.
Tributes from the fashion and entertainment industries have flooded in, with the British Fashion Council describing her as "an iconic woman who inspired so many".
© UTV News