Kristin’s parents separated when she was only 6 months old. Her mother Dorothy remarried Keith Davis and she was adopted by her stepfather. She along with her parents relocated to Columbia, South Carolina. She stayed in South Carolina, until her high school after which she enrolled at Rutgers University and thereafter she relocated to New York, where she acted in both contemporary and classical theatre and also starred in commercials.
Kristin landed her first major role in the television series Melrose Place in 1995. Her portrayal of Brooke Armstrong Campbell earned her a lot of accolades and adulation from the viewers. After which she starred in the famous television Sex and the City in 1998. She remained with the show till it ended in 2004. She reprised her role of Charlotte York in the feature film Sex and the City in 2008 and again in Sex and the City 2 in 2010.
In addition to acting in films and television series, she has performed as a stage actress as well. She landed her first Broadway role in reprised Gore Vidal's, The Best Man in 2012.
She has been associated with several philanthropic works worldwide and she also served as the brand ambassador of Oxfam, since 2004. To support their campaign she has travelled to countries like Mozambique, Haiti and South Africa. She has also worked with UNHCR (United Nations High Commissioner for Refugees). To support UNHCR, she has released a film to raise fund for this organisation.
Off Screen, she has been linked to several men such as Steve Martin and Alec Baldwin, among others, but to date is unmarried.