Spade, 55, was found in her Park Avenue apartment at around 10:20 a.m. Tuesday morning.
She was discovered by her housekeeper and appeared to be hanging. A note was found nearby.
Spade created a line of sleek handbags in the early 1990s that created a smash. Her company, Kate Spade New York, has over 140 retail shops and outlet stores across the U.S. and more than 175 shops internationally.
She walked away from the company in 2007, a year after it was acquired from the Neiman Marcus Group for $125 million by the company then known as Liz Claiborne Inc. In 2017, Coach bought the brand for $2.4 billion.
Spade and her husband Andy started a new handbag company a few years ago, Frances Valentine. And she changed her name to Katherine Noel Frances Valentine Brosnahan Spade, she said in an NPR interview this year.
In addition to her husband, Spade is survived by a daughter, born in 2005.
If you or someone you know is struggling with thoughts of suicide, please reach out for help:
National Suicide Prevention Lifeline: 1-800-273-8255
Crisis Text Line: text BUDDY to 741-741 for free, 24/7 support