[1] Karan and her older sister Gail were raised by their mother in Woodmere, in the Five Towns region of Nassau County, New York.

As Klein's assistant, Karan was a participant in The Battle of Versailles Fashion Show on November 28, 1973.

When Klein herself died in 1974, Takihyo Corporation of Japan became the new owner and Karan, together with her former classmate and friend Louis Dell'Olio, became head designer of the house.

[11] Karan became well known for her 'Essentials' line, initially offering seven easy pieces centered around the bodysuit which could all be mixed and matched, and created a fully integrated wardrobe with her First Collection in 1985.

Karan always insisted that she would design only clothes like jersey dresses and opaque Lycra tights that she would wear herself.