Williams was raised in Rosemount, Minnesota where her father, Les, was a middle school math teacher. She was crowned as Minnesota's Junior Miss in 1985, and graduated from Rosemount High School shortly thereafter. Williams was active in theatre. Her classmates described her as smart, friendly and motivated, but most did not know her potential comedy skills.
Williams attended the University of Minnesota and was active in her sorority, Alpha Phi. She wrote and starred in her campus carnival talent skits and moved to Los Angeles after her graduation.
She started her career as an assistant on The Simpsons, occasionally doing voices, such as the voice of Amber Dempsey, a single-episode character from "Lisa the Beauty Queen". She later worked on The Drew Carey Show as a writer and producer. She went on to write the screenplay for the film Drop Dead Gorgeous.