Although Kelly was born in New York, she spent most of her childhood in London in United Kingdom. Her father is of French – Canadian origin. He used to own a 3 star Michelin restaurant in New York named The General Thurber Inn. Her mother is of Irish origin and she also used to be a model, who probably inspired Kelly to choose that career. She also used to run several antique stores in UK. After spending almost 15 years in London, Kelly returned to New York in 1976 at the age of 16 to begin her career as a model. She later stated that she was afraid of the various drug abuse rampant in England and that’s why she returned to New York, but she later realised New York is no different.

Her modelling career soon became a success and she was one of the best and most popular models at that time. She appeared in several magazines and advertisements for various brands all over the world. She also appeared for an exclusive campaign for Christian Dior. She was the most popular model of Eileen Ford at that time. One of her lines in an advertisement for Pantene – “Don't hate me because I'm beautiful" has become a very popular catchphrase. She said that she used to take this job too seriously – her weight reduced from 135 lbs to a mere 90 lbs for this career. She decided that she probably won’t be able to handle the pressure and stress of modelling and hence decided to leave modelling in favour of movies.

Her acting debut occurred in the movie “The Woman In Red”. She played the role of a women who is perfect from all sides and is more of a fantasy girl in the movie. She played a similar role in the movie “Weird Science”. These sort of roles were crucial to her reputation as one of the hottest Hollywood actresses in the 80s. She was seen in a few more movies such as “Hard To Kill”, “Betrayal Of The Dove” etc. but gradually left acting as well.

Kelly has 3 husbands till date. She started dating film producer, Victor Drai in 1983 and married him next year. Their marriage ended in divorce only after 2 years. She married Steven Seagalin 1987. She gave birth to 3 children during her marriage to Steven, but unfortunately their marriage ended in 1996. She recently married Fred Steck in 2007.

She is also a philanthropist and is the spokesperson of a charity for children affected with cancer.

Her estimated net worth is over $2 million, as of 2015.