Spade was known for her bright accessories line and her distinct playing card symbol, as well as for designing clothes, jewellery, shoes and other items.
In 1993, she co-founded Kate Spade Handbags with her husband Andy Spade, opening a store in New York in 1996 and going on to create 300 branches across the world.
They sold the brand in 2007, and Kate went on to raise her daughter and later start a new brand, Frances Valentine.
She is a former editor of fashion magazine Mademoiselle, where she saw a gap in the market for sensible and stylish handbags.
Celebrities and well-known individuals are tweeting about their first Kate Spade handbags and what the designer meant to them. Chelsea Clinton tweeted that her grandmother gave her her first Kate Spade bag when she was in college.
My grandmother gave me my first Kate Spade bag when I was in college. I still have it. Holding Kate’s family, friends and loved ones in my heart.
— Chelsea Clinton (@ChelseaClinton) June 5, 2018
Lena Dunham tweeted that Spade was a “staple of New York” and that she had spread much good will.
Mindy Kaling said she is “heartbroken” to learn the news, and had worn Kate Spade clothes many times. “They were colourful, bold, cheerful, and encouraged women to find the twinkle person inside them’
Kate Spade was 55.
Police are not reporting any suspicious circumstances behind her death.
I am heartbroken about the news of Kate Spade. I have worn her clothes many, many times. They were colorful, bold, cheerful, and encouraged women to find the twinkly person inside them. You couldn’t walk into her boutiques and not smile. Rest In Peace, Kate.
— Mindy Kaling (@mindykaling) June 5, 2018
Lifeline: 13 11 14.