O'Connor's time as singer for Ton Ton Macoute brought her to the attention of the music industry and she was signed by Ensign Records. She also acquired an experienced manager, Fachtna O'Ceallaigh, former head of U2's Mother Records. Soon after she was signed she embarked on her first major project, providing the vocals for the song "Heroine", which she cowrote with U2's guitarist The Edge for the soundtrack to the film Captive. While she was building bridges she was also burning them. O'Ceallaigh, who had been fired by U2 for complaining about them in an interview, was outspoken with his comments about music and politics, and O'Connor began to adopt the same habits, making controversial comments about the IRA and even directing negative remarks towards U2, who were admirers of her music.

Things were contentious in the studio as well. She was paired with veteran producer Mick Glossop, whom she later derided as "a fucking old hippy". They had differing visions regarding her debut album and four months of recordings were scrapped. During this time she became pregnant by her session drummer John Reynolds (who went on to drum with the band Transvision Vamp) and the record company pressured her to get an abortion. Thanks largely to the persuasion of O'Ceallaigh, the record company allowed O'Connor, 20 years old and by then seven months pregnant, to produce her own album.

O'Connor's first two albums (1988's The Lion and the Cobra and 1990's I Do Not Want What I Haven't Got) gained considerable attention and mostly positive reviews. She was praised for her unique voice and her original songs. She was also noted for her appearance: her shaved head, angry expression, and sometimes shapeless or unusual clothing.

The Lion and the Cobra was not embraced by the pop mainstream, although the singles "Mandinka" and "I Want Your (Hands on Me)" became minor hits, the latter as a remix to which American female rapper MC Lyte added verse. The following year O'Connor joined The The frontman Matt Johnson as a guest vocalist on the band's album Mind Bomb, which spawned the duet "Kingdom of Rain" and the minor hit "The Beat(en) Generation".

I Do Not Want What I Haven't Got contained her biggest hit single, "Nothing Compares 2 U", a song written by Prince . The track hit #1 in Ireland in July 1990 and remained there for eleven weeks; it is the eighth most successful single of the decade there. It had similar success in the UK, charting at #1 for three weeks, and in Germany (#1 for eleven weeks). In Australia it reached #1 on the Top 100. It also claimed the #1 spot on the Hot 100 chart in the USA.

Public Enemy's Hank Shocklee remixed "The Emperor's New Clothes" that was coupled with the Celtic funk of "I Am Stretched On Your Grave." Pre-dating but included on I Do Not Want What I Haven't Got was "Jump in the River" (which originally appeared on the Married to the Mob soundtrack); the 12-inch version of the single included a remix featuring performance artist Karen Finley in signature X-rated form.

Also in 1990 she joined many other guests for former Pink Floyd member Roger Waters' massive performance of The Wall in Berlin. (In 1996, she would guest on Broken China, a solo album by Richard Wright of Pink Floyd.) In 1991 her take on Elton John's "Sacrifice" was acclaimed as one of the best efforts on the tribute album Two Rooms: Celebrating the Songs of Elton John & Bernie Taupin.

In 1992, she contributed a cover of "You Do Something to Me" to the Cole Porter tribute/AIDS fundraising album Red Hot + Blue. This was followed by the release of Am I Not Your Girl?, an album of standards and torch songs that she had listened to while growing up. Her interpretations were considered to run from sublime to overwrought to bizarre, and - coupled with her Garden State Arts Center controversy (see below) - the record lost for her much of the commercial momentum her career had built up until then.

After spending nine years dividing her time between London and Los Angeles, O'Connor returned to her home town of Dublin in late 1992 to live near her sister and focus on raising her son Jake, then 6 years old. She spent the following months studying Bel Canto singing with teacher Frank Merriman at the Parnell School of Music. In an interview with The Guardian published May 3, 1993 she reported that her singing lessons with Merriman were the only therapy she was receiving, describing Merriman as "the most amazing teacher in the universe."

The 1993 soundtrack to film In the Name of the Father featured "You Made Me the Thief of Your Heart," with significant contributions from Bono of U2.

1994's more conventional Universal Mother did not succeed in restoring her mass appeal, though its opener, "Fire On Babylon," remains a fan favourite. She toured with Lollapalooza in 1995, but dropped out when she became pregnant. O'Connor was replaced on the bill by Elastica.

Faith and Courage from 2000, largely regarded as a return to form, included the single "No Man's Woman" and featured contributions from Wyclef Jean of the Fugees and Dave Stewart of Eurythmics. Many songs on the album centre around the theme of healing. On the eve of its release she came out as a lesbian, and then retracted the statement.

Her 2002 album, Sean-Nós Nua, marked a departure in that O'Connor interpreted or, in her own words, "sexed up" traditional Irish folk songs, including several in the Irish language[2]. In 2003, she contributed a track to the Dolly Parton tribute album Just Because I'm a Woman, a cover of Parton's "Dagger Through the Heart". That same year, she also released a double album, She Who Dwells in the Secret Place of the Most High Shall Abide Under the Shadow of the Almighty. The album contained one disc of demos and previously-unreleased tracks and one disc of a live concert recording. Directly after the album's release, O'Connor announced her retirement from music.[3]

This proved to be short-lived, as the reggae album Throw Down Your Arms appeared in 2005, greeted with very enthusiastic reviews, critics considering it one of O'Connor's best albums. It was based on the Rastafarian culture and lifestyle, O'Connor having spent time in Jamaica in 2004. She performed the single "Throw Down Your Arms" on The Late Late Show in November, but was not well received, embarrassing host Pat Kenny and placing her bare feet on the chair beside her. She also made comments critical of the war in Iraq and the role played in it by the Irish airport Shannon.

She is currently working on a collection of her own spiritual songs to be entitled Theology, for release in April 2007. The album will consist of two discs with the same songs, but performed just with acoustic guitar and voice on one, and with full band and production (Ron Tom) on the other.

--Wikipedia