Gaither officially joined the cast of MADtv in 2003, seven years after her initial appearance on the series, as a feature performer for the ninth season. She became the second African American female cast member in the show's history, when she replaced Debra Wilson. Gaither was later promoted to a repertory performer status the following season.
While she studied at the Groundlings school, Gaither was trained by Michael McDonald, before his tenure on MADtv. She completed the school and became a member of The Groundlings on Melrose Avenue in Hollywood. After several years as a member, she left the group in 2006.
In her comedy, Gaither tries to "represent people that you see in the streets and know in everyday life," and sometimes uses her family experiences as material. She does impressions of people that she grew up admiring, such as Patti Labelle, Marla Gibbs and Isabel Sanford, but also does impressions of current celebrities like Oprah Winfrey, Star Jones and Lil' Kim.