Upon signing a contract with Ensign Records in 1985, O'Connor relocated to London; the following year she made her recorded debut on the soundtrack of the film The Captive, appearing with U2 guitarist the Edge. After scrapping the initial tapes for her debut LP on the grounds that the production was too Celtic, she took the producer's seat herself and began re-recording the album, dubbed The Lion and the Cobra in reference to Psalm 91; the result was one of the most acclaimed debut records of 1987, with a pair of alternative radio hits in the singles "Mandinka" and "Troy." Almost from the outset of her career, however, O'Connor was a controversial media figure; in interviews following the LP's release, she defended the actions of the IRA, resulting in widespread criticism from many corners, and even burned bridges by attacking longtime supporters U2, whose music she declared "bombastic."

However, O'Connor remained a cult figure prior to the release of 1990's chart-topping I Do Not Want What I Haven't Got, a harrowing masterpiece sparked by the recent dissolution of her marriage to drummer John Reynolds. Boosted by the single and video "Nothing Compares 2 U," originally penned by Prince, the album established her as a major star, but again controversy followed as tabloids took aim at her romance with black singer Hugh Harris while continuing to attack her outspoken politics. On American shores, O'Connor also became the target of derision for refusing to perform in New Jersey if "The Star Spangled Banner" was played prior to her appearance, a move which brought public criticism from no less than Frank Sinatra, who threatened to "kick her ass"; she also made headlines for pulling out of an appearance on the NBC program Saturday Night Live in response to the misogynist persona of guest host Andrew Dice Clay, and even withdrew her name from competition in the annual Grammy Awards despite four nominations.

O'Connor also continued to confound expectations with her third album, 1992's Am I Not Your Girl?, a collection of pop standards and orch songs that failed to live up to either the commercial or critical success of I Do Not Want What I Haven't Got. However, any discussion of the record's creative merits quickly became moot in the wake of her most controversial and damaging action yet: after finally appearing on Saturday Night Live, O'Connor ended her performance by ripping up a photo of Pope John Paul II, resulting in a wave of condemnation unlike any she'd previously encountered. Two weeks after the SNL performance, she appeared at a Bob Dylan tribute concert at New York's Madison Square Garden, and was promptly booed off the stage.

Now a virtual pariah, O'Connor's retirement from the music business was subsequently reported, although it was later claimed that she had merely returned to Dublin with the intent of studying opera. She kept a low profile for the next several years, starring as Ophelia in a theatrical production of +Hamlet and later touring with Peter Gabriel's WOMAD festival. She also reportedly suffered a nervous breakdown and even made a half-hearted attempt at suicide. In 1994, however, O'Connor returned to pop music with the LP Universal Mother, which, despite good reviews, failed to relaunch her to superstar status; the following year she announced that she would no longer speak to the press. The Gospel Oak EP followed in 1997, and in mid-2000 O'Connor issued Faith and Courage, her first full-length effort in six years. Sean-Nós Nua followed two years later, and was widely hailed for its return to the Irish folk tradition as its inspiration.

O'Connor used the press exposure from the album to further assert her pending retirement from music. In September 2003, the two-disc She Who Dwells... appeared through Vanguard. It collected rare and previously unreleased studio tracks, as well as live material culled from a late 2002 date in Dublin. The album was positioned as O'Connor's swan song, though official word was not forthcoming. Collaborations followed in 2005, a compilation of appearances on other artists' records throughout her long career. Later that year she released Throw Down Your Arms, a collection of eggae classics from the likes of Burning Spear, Peter Tosh, and Bob Marley that managed to reach the number four spot on Billboard's Top Reggae Albums chart. O'Connor returned to the studio the following year to begin work on her first album of all-new material since Faith and Courage. The resulting Theology, inspired by the complexities of the world post-9/11, was released in 2007 through Koch Records on the artist's own imprint, That's Why There's Chocolate and Vanilla. ~ Jason Ankeny, All Music Guide