Dublin born Eimear Quinn joined her first choir at four years of age and at fifteen she started formal vocal training under the tutelage of Jody Beggan. She graduated with a degree in Music from National University of Ireland Maynooth. While studying for her degree she developed an interest in early music and was a founder member of the ensemble Zefiro.
In 1995 she joined the choir Anúna. She recorded two albums Omnis (1996) and Deep Dead Blue (1996), featuring as a soloist on a number of tracks. She also toured internationally with the choir participating in performances in Spain, France and the UK. It was while singing with Anúna in St Patrick's Cathedral in Dublin at Christmas 1995 that songwriter Brendan Graham heard her and invited her to sing his composition "The Voice" as Ireland's entry for the Irish Eurosong competition. Her performance won, and she then travelled to Oslo and was victorious in the Eurovision Song Contest 1996. Quinn began touring solo, performing in Australia, America and all over Europe in venues including The Royal Albert Hall, The Sydney State Theatre and the Forest National Brussels. She also made many television appearances and also presented Television and Radio programming for RTÉ and TV3.
Quinn has collaborated with a number of international composers on a range of musical and television projects. These have included performing and co-writing the score to Belgian drama series
Stille Waters with Steve Willaert. She performed "Voice of an Angel" on Liam Lawton's album Another World.
In 2006 Quinn released the album Gatherings, a collection of music she had recorded over the previous decade. This was Eimear's third solo disc and followed Winter Fire and Snow and Through the Lens of a Tear, an album she co-wrote with Pol Brennan of Clannad, who also produced the album. Quinn performed "The Voice" later that year while appearing at "Ireland's Finest in Concert", a gala celebration of the 25th anniversary of the National Concert Hall. This performance was broadcast on RTÉ television and the concert has been released as a DVD.
In 2007, Quinn was chosen by the National University of Ireland to promote the studying of Music at NUI Maynooth in a nationwide campaign. The same year she worked with the film-maker, Philip King to complete a documentary on the subject of her music and collaboration with Belfast-born composer, Neil Martin for RTÉ1 Television.
December 2007 saw the release of O Holy Night a collection of carols, ancient chants and new compositions from Quinn, who also produced and arranged the album with Martin Quinn at JAM Studios. This led to her presenting a television special A Christmas Celebration with Eimear Quinn on RTÉ1 Television in December 2008.
Since then Quinn has been touring and composing. In 2011 she was asked to perform for England's Queen Elizabeth to mark her State Visit to Ireland. In August 2012 she performed at The Gathering concert in the O2 in Dublin. She performed a special concert with the Symphony Orchestra in the National Concert Hall, Dublin in October 2012. She has also performed at other state occasions such as the Royal Albert Hall event in April 2014 to celebrate the state visit of Irish President Michael D Higgins to the UK.
In October 2013 she featured as part of the RTÉ Big Music Week Ensemble. The group which also included Marianne Knight, Nono Madolo and Celine Byrne, along with the RTÉ Concert Orchestra and the UCD Choral Scholars, released The Fair, Fair Land. The track, which was composed by Brendan Graham, was in aid of the Barnardo's children's charity.
In a radio interview on RTE's Radio 1 in November 2016, she said that, even though she still toured at least once a year, she had scaled back her professional commitments a little after having two children. She also said in the interview that she felt the time was right now to write, perform and tour more again and she confirmed that she is currently composing new material for an album that will be released in 2017. She was promoting her December Irish tour.