She was born Mary Lynn Rajskub on June 22, 1971, in Detroit, Michigan, into a family of Irish, Czech, and Polish ancestry. She was brought up in Trenton, Michigan. In 1989 she graduated from Trenton High School, then attended Detroit's College for Creative Studies, majoring in painting, before she transferred to the San Francisco Art Institute, graduating as a painter. She also studied music and acting, and for a few years she performed as a stand-up comedian at various clubs and restaurants. In 1995, Rajskub made her debut on television, she was cast by David Cross as one of the original cast members of Mr. Show with Bob and David (1995). After her split from Cross, she left the show during its second season, and briefly took a job as a coffee brewer at Seattle's Best Coffee. In 1999 she joined the cast of 'Veronica's Closet' TV series, as Cloe, appearing in 15 episodes of the show.