Witt was born in Worcester, Massachusetts, the daughter of Diane, a junior high school reading teacher, and Robert Witt, a science teacher and photographer. She was home schooled by her parents. Witt was introduced to a larger audience playing the role of Zoey Woodbine, daughter of actress Cybill Shepherd's character in the sitcom Cybill from 1995 to 1998. In 2000, Witt had starring roles on the television shows Ally McBeal and The Sopranos. Witt has joined the cast of Law & Order: Criminal Intent for the 2007-08 season as Det. Nola Falacci.