She was born in Dundalk, Ireland, the youngest daughter of Jean and Gerry Corr, two musicians. She and her elder siblings, sisters Caroline (Born 1973) and Sharon Corr (Born 1970) and brother Jim (Born 1964), formed The Corrs to audition for the 1991 film The Commitments. Although all four appeared in the film, Andrea was the only one to be given a speaking part. But several years later, in another fleeting appearance in a major film, she was wanted strictly for a singing role - it was the musical Evita, in which she played Juan Peron's mistress, who is abruptly displaced by Madonna's title character. She stands 5'1" tall, making her the shortest of the four Corr siblings.

In 2002, a chance for Andrea to launch a more extensive acting career appeared to open up, as she was strongly rumoured to have been offered the role of Lara in a fresh British television production of Boris Pasternak's classic novel Doctor Zhivago. The character was however ultimately played by the then little-known Keira Knightley. Andrea is thought to have turned down the opportunity after learning the part required her to appear nude in several scenes. This decision was consistent with a well-known ambivalence towards the role that her sexuality plays in her career. On the one hand, she has maintained a strict policy of remaining fully-clothed for any photo-shoots she takes part in, despite numerous lucrative offers to tempt her to disrobe to some degree, and famously responded to being voted 'Ireland's Sexiest Woman' by appearing to rather piously chide anyone that might actually have voted for her, remarking that she hoped they didn't just want to sleep with her. On the other hand, she has openly admitted on a number of occasions that she and her sisters have sought to harness their beauty for its potential to build the band's profile, by for instance adopting sultry poses in their videos and photo-sessions.

As the youngest member of the band, Andrea joined it directly from school, not having the chance to move into a flat of her own until the age of twenty-five. She has confessed to the distinctive habit of sucking her thumb for reassurance, and for recreation enjoys cooking, reading and going for walks. In addition, she has taken to doing live performances barefoot.