Vaughn was born in Idabel, Oklahoma to Sandra and Leo Vaughn. She began her performing career at the age of three in 1981 singing at church. At age nine in 1988, she sang "I'll Be There" to win the Star Search junior vocalist champion and overall junior champion. Following that success, she was cast as Alexandria DeWitt in the fourth season of NBC sitcom, 227.
In 1990s, Vaughn guest starred on Thea, Hangin' with Mr. Cooper, and Roc. Outside of television, she performed in the off-Broadway musical Mama, I Want to Sing! Part 3. In 1992, Vaughn released her first album, Countess, featuring a variety of songs, including dance music and R&B. The album's lead single, a cover of James Brown's "It's A Man's, Man's, Man's World", charted in the top-100 of the Billboard R&B/Hip-Hop Songs chart; the album itself sold 3,000 copies.
Vaughn is best known for her role as Kimberly Ann Parker in the UPN sitcom Moesha. She starred on the show from 1996 to 1999. In 1998, Vaughn was honored with an NAACP Image Award for Outstanding Supporting Actress in a Comedy Series for her performance in Moesha. She starred in and also sang the theme song for its spin-off, The Parkers, opposite Mo'Nique. The series aired from 1999 until 2004. In film, she co-starred in Trippin (1999). In later years she guest starred on Cuts and Let's Stay Together
She was married to Joseph James, with whom she has a son Jaylen. During an appearance on The Mo'Nique Show, as well as The Doctors, she shared that she also has a daughter. In 2014, Vaughn appeared on The Doctors and revealed she suffered from hair loss due to bad reactions from glue used on wigs she wore for many years. She also has discoloration on her skin in many places.
As of mid-2000s, Vaughn began appearing in a number of reality shows. She appeared in the third season of Celebrity Fit Club which premiered in January 2006 on VH1. On episode four,she announced that she and husband, James, were ending their marriage. During the course of the show, she became the first cast member to ever gain weight, with a weight gain of 2 pounds. It was said on the season finale that she was simply trying to lose weight at the wrong time. She later appeared as a contestant on MTV's Celebrity Rap Superstar which premiered August 30, 2007. She studied under Warren G for the show. On September 27, 2007, an illness caused her to be eliminated from the competition.
In 2014, Vaughn began starring in the TV One reality series Hollywood Divas, alongside Golden Brooks, Lisa Wu, and Paula Jai Parker. The series premiered on October 8, 2014. She is one of the black actresses trying to navigate their career, family and relationships, while attempting to stay relevant in an unpredictable entertainment industry known for overlooking black talent. During the first season, Vaughn revealed that she had an abortion around the age of 18. She said that “I had an unwanted pregnancy. I had just started my TV show. I knew that in black Hollywood a girl having a baby, they’d get rid of you. I had to do something about it. I had to make a decision to get rid of a child for my career.”