Kate Walsh was born in San Jose, Calif., and grew up in Tucson, Ariz. She was raised in an Irish-Italian Catholic home, and attended the University of Arizona, where she became involved in regional theater.
Walsh was a model in Japan during the 1980s. After college, she moved to Chicago, where she began working with the Piven Theatre Workshop. Kate performed on NPRin the production of the radio play Born Guilty.
Walsh subsequently moved to New York City and joined the comedy troupe Burn Manhattan on June 27, 1987, performing in a number of Off-Broadway plays.
Her first major TV appearance was in 1997, when she appeared on The Drew Carey Show as Carey's character's girlfriend Nicki. She wore a fatsuit in some episodes of the show, as Nicki was a formerly obese woman who lost weight and slowly started to gain it back.
She went on to portray Carol Nelson in HBO's The Mind of the Married Man TV series, and played Norm MacDonald's romantic interest in the sitcom "The Norm Show." Walsh also made a notable guest appearance on CSI: Crime Scene Investigation as Mimosa, a transsexual.
She sometimes appeared in sketches on Late Night with Conan O'Brien, and had a recurring role on Karen Sisco as Detective Marley Novak in 2003 and 2004.
The crime drama Normal Life marked her film debut; she played the sister of a bank robber played by Luke Perry. She portrayed a kleptomaniac in the film Peppermills.
Walsh also appeared in the cult movie, Henry: Portrait of a Serial Killer, Part 2. She had her first significant role in a major Hollywood production as Will Ferrell's wife in the family comedy, Kicking & Screaming, along with Robert Duvall and Mike Ditka.
Walsh has also appeared in several other films with Ferrell, including Bewitched and an "alternate film" to Anchorman entitled, Wake Up, Ron Burgundy: The Lost Movie.
In 2003, Walsh appeared in Under the Tuscan Sun, with Diane Lane and Sandra Oh. She played the girlfriend of Sandra Oh's character, going on to star in Grey's Anatomy with Oh two years later.
In 2005, her big break came on Grey's Anatomy as Dr. Addison Montgomery-Shepherd, the estranged spouse of Derek Shepherd (Patrick Dempsey). The role of Addison was originally conceived as a short-term role, but the viewers' response to the Derek/Meredith/Addison love triangle convinced creator Shonda Rhimes to expand the role and make Walsh a regular.
It was announced in February 2007 that Walsh and the character of Addison would star in a spin-off of Grey's Anatomy to air in the fall of 2007, entitled Private Practice.
A natural blonde, Kate says she went to red hair because she never was a blonde at heart. "Being blonde was always other than what I really am. I thought I wanted to be one of those softer, girly girls. Then I grew out of that. I realized I’d never be a sweet girl. Never."
She is the current spokeswoman for Caress and their new line of body wash called Exotic Oil Infusions. She recently appeared on the cover of O at Home (the homestyle magazine by Oprah Winfrey) and was credited as being their first cover girl for that magazine.
In May 2007, Kate Walsh got engaged to Alex Young, a production co-president at 20th Century Fox.