Williams was born in Millwood, New York where she and her brother grew up in a suburban area. Prophetically, her parents put "Here she is: Miss America" on her birth announcement.

Her parents, Milton and Helen Williams, were both music teachers.

Vanessa studied piano and French horn growing up, but was most interested in singing. She received a scholarship and attended Syracuse University as a theatre arts major, but later dropped out of college to pursue a career in entertainment. She also won scholarships for being selected as Miss America.

Williams began competing in beauty pageants in the early 80s, and won Miss New York in 1983. She then went on to Atlantic City where she was crowned Miss America 1984 on September 17, 1983, making her the first ever African-American Miss America. Prior to the final night of competition, Williams won both the Preliminary Talent and Swimsuit Competitions earlier in the week.

Controversy erupted in the summer of 1984 when it was discovered that in 1982 she had posed nude for photographs — including scenes of graphic exposure and lesbian theming — that were about to be published in the September 1984 issue of adult magazine Penthouse without her permission. After several days of media frenzy, Williams chose to resign her position on July 23, 1984. The crown was given to Suzette Charles (making her the second African-American Miss America), 54 days before the start of the pageant for Miss America 1985. At the time, many believed Williams' reputation would never recover from the scandal.

Four years later, she appeared in the music industry with her 1988 debut album, The Right Stuff, which reached gold status and earned her three Grammy Award nominations, including one for Best New Artist.

Her most notable songs include "Dreamin'", "Running Back To You", "Love Is", "The Sweetest Days", "Colors of the Wind", "The Comfort Zone" and "Oh How The Years Go By". However, her biggest hit to date and signature song is "Save the Best For Last", which topped the Billboard Hot 100 for five weeks from March 21 to April 18, 1992. In total, Williams has sold six million records and received fifteen Grammy Award nominations.

In 2005, Vanessa released her eighth studio album, Everlasting Love, a collection of covers of her favorite 1970s songs.

In the 80s, she also began a career in acting with guest roles in tv series, such as The Love Boat, T.J. Hooker and The Fresh Prince of Bel-Air, and roles in made-for-TV movies, such as Perry Mason: The Case of the Silenced Singer and The Jacksons: An American Dream.

Her other TV appearances include Saturday Night Live, Star Trek: Deep Space Nine, LateLine, Ally McBeal and Boomtown.

She played the nymph Calypso in the 1997 Hallmark Entertainment miniseries The Odyssey, starring Armand Assante.

She later won starring roles in feature movies, such as Eraser, co-starring Arnold Schwarzenegger, Soul Food, for which she won the Best Actress award at the NAACP Image Awards, and Dance With Me.

Her other movies include Hoodlum, opposite Laurence Fishburne, Adventures of Elmo in Grouchland (as the Queen of Trash), Shaft, opposite Samuel L. Jackson, and Johnson Family Vacation, alongside Cedric the Entertainer.

Williams has appeared in several Broadway theatre productions, including major roles in Kiss of the Spider Woman in 1994 for which she received favorable reviews and Stephen Sondheim's Into the Woods in 2002.

She has also appeared in a number of advertisements for Radio Shack, starting in 2001. Recently Williams has become the spokesmodel for Proactiv Solution. In early 2006 she starred in the short lived UPN drama South Beach. For the Fall 2006 season, she will be starring in the new ABC comedy Ugly Betty, produced by Salma Hayek.

Williams has been married twice. Her first marriage to her then-manager Ramon Hervey ended in 1997. She married again in 1999 to NBA basketball star Rick Fox, previously of the Los Angeles Lakers. She is the mother of four children: Melanie Lynne (born 1987), Jillian Kristin (born 1989), Devin (born 1993), with Hervey; and Sasha Gabriella (born 2000), with Fox.

After The National Enquirer published pictures of Fox kissing another woman in mid-2004, Fox's representatives announced that the couple had been "headed toward divorce" for over a year. A few months later on August 10, Fox filed for divorce. During some press interviews, Williams cast some doubt on the status of their relationship. But while visiting the Howard Stern radio show in early 2005, she said that while she and Fox were intimate with each other briefly during the holidays, a reconciliation was unlikely. In early 2006, Williams began dating 29-year-old actor Rob Mack, whom she met on the set of her show South Beach.