A classically trained dramatic actress, Foster studied acting at New York University's Tisch School of the Arts. She later performed in many off-Broadway and regional productions, including “The Democracy Project” with Naked Angels and was awarded Best Actress for her performance in “Final Countdown” at the 2003 New York International Fringe Festival. An active member of the New York theater community, she participated in extensive readings and workshops at the Manhattan Theater Club, MCC Theater, New York Theatre Workshop and The Public Theater, among others.
Past TV appearances include roles on Family Guy, The Book of Daniel, Law & Order, 'Til Death, and Law & Order: Criminal Intent. In addition, she starred with Bobby Cannavale and Donnie Wahlberg in the NBC pilot NY-70, a stylized police show set in the 1970s, and the CBS pilot Webster Report, about a reluctant New York detective, also with Cannavale and Stanley Tucci.
- The Education of Max Bickford (1 episode, "Herding Cats", 2001) .... Jackie Kramer (as Kathy Foster)
- Thanksgiving (2004) .... Nadine (as Kathy Foster)
- N.Y.-70 (2005) (TV) .... A.D.A. Rachel Abramowitz
- Law & Order: Criminal Intent (1 episode, "The Unblinking Eye", 2005) .... Kelly West
- Law & Order (1 episode, "Acid", 2005) .... Justine
- The Book of Daniel (1 episode, "Forgiveness", 2006) .... Michelle Hedley]
- Family Guy Video Game! (2006) (VG) .... Carolyn (voice)
- Family Guy (1 episode, "Love Blactually", 2008) .... Carolyn (voice)
- 'Til Death (40 episodes, 2006–2008) .... Steph Woodcock
- Eva Adams (2009) (TV) .... Grace Wainright
- The Unusuals (5 episodes, "Pilot", "One Man Band", "The Dentist", "The Apology Line" and "The E.I.D.", 2009) .... Nicole Brandt
- The Good Wife (1 episode, "Infamy", 2010) .... Emily Tartan