Vaughn began her performing career at the age of three singing at church. At age nine, she sang the Burt Bacharach and Hal David's "What the World Needs Now is Love, Sweet Love" to win the Star Search junior vocalist champion and overall junior champion. She claims among her musical influences gospel singer Mahalia Jackson, jazz and blues singer Dinah Washington, and R&B/pop singer Whitney Houston.

Vaughn began her acting career in 1988 with the role of Alexandria DeWitt on 227, followed by roles in The Fresh Prince of Bel Air, Thea, Hangin' with Mr. Cooper, and Roc. She also performed in several television specials including the Lou Rawls Parade of Stars, Magical World of Disney, the Orange Bowl Parade, the Easter Seals Telethon. Outside of television, she performed in the off-Broadway musical Mama, I Want to Sing, Part 2. In 1998, Vaughn was honored with an NAACP Image Award for Outstanding Supporting Actress in a Comedy Series for her performance in Moesha. In 1992, Vaughn released her first album, Countess, featuring a variety of songs, including dance music and ballads. In 2003, Vaughn and husband Joseph James had their first child, a boy named Jaylen James.

Vaughn appeared in the third season of Celebrity Fit Club that premiered in January 2006 on VH1. On episode four, she revealed she and James were undergoing a divorce. During the course of the show, she became the first cast member to ever gain weight, with a weight gain of 4 pounds. It was said on the season finale that she was simply trying to lose weight at the wrong time.