Gibson was born in 1970 in Brooklyn, New York. At the age of five, she and her sisters began performing in a community theater, and she wrote her first song. When she was eight, she sang at the children's chorus in the Metropolitan Opera House in New York, where she got to meet such singers as Plᣩdo Domingo and others. When she was 12, Gibson was already performing in Broadway, but as an actress.

When Gibson turned 16, she was signed to a recording contract by Atlantic Records, and soon she became the youngest person ever to write, record and produce a number 1 hit, with her single "Foolish Beat", going up to number one. Another single of hers, "Only In My Dreams", also made it to the top.

Her initial success was followed by another smash hit in "Out Of The Blue". By this time, she and Tiffany, with her remake of "I Think We're Alone Now", were fighting for the top position as teen queen of the United States. She also had considerable success in the UK, as well as Japan and south east Asia.

After her popularity as a pop singer waned, she returned to Broadway in 1992, playing Eponine in Les Mis鲡bles. She then went to London, where she played Sandy in a West End production of Grease. To go with her stage performance, she also helped record the soundtrack for the play, titled "Grease: The Original London Cast Recording". From that CD, came a hit single with Craig McLachlan: "You're the One That I Want", which reached #13 on the UK charts in 1993.

On returning to the States, she also participated in the Broadway version, but this time she played Rizzo. She also played Fanny Brice in the Funny Girl touring production. She also participated in the Broadway production of Beauty and the Beast (as Belle), and Gypsy at The Papermill Playhouse (as Gypsy Rose Lee). She also participated in a national tour with Joseph and the Amazing Technicolor Dreamcoat, where she played the character of The Narrator, and as Cinderella in the national tour of the play of the same name. In October 2002, she began work in the play Chicago in Boston.

In 1995, she signed with EMI Records' SBK Records division and recorded what would be her only album for the label, Think With Your Heart. The album's producer, Niko Bolas (usually Neil Young's co-producer), was also producing the reunion album for veteran punk band The Circle Jerks, and invited Gibson to a recording session for that band's album. She subsequently ended up singing background vocals on the song "I Wanna Destroy You" as well as appearing at and participating in the Circle Jerks' performance at legendary punk venue CBGB's, wearing one of the band's t-shirts and sharing a microphone with frontman Keith Morris. (Unfortunately for posterity, the show, with the exception of photographs, wasn't recorded, nor was Gibson able to participate in the video the group shot for the song.)

After parting company with EMI, Gibson formed her own record label to release her original material.

Controversially for some of her fans who were more comfortable with her earlier wholesome image, the March 2005 issue of Playboy featured a nude pictorial with Gibson, the publication of which also coincided with the release of her single, "Naked."