The band has had thirteen UK number-one singles between the years 1999 and 2005, the fourth-highest such total of all time (trailing only Elvis Presley, The Beatles, and Cliff Richard). They also had their first seven singles ever released reach number one, a record (once held earlier for two decades by Gerry & the Pacemakers), and furthermore each of these singles entered the charts at number one.
The bands' origins are in Sligo in northwest Ireland, where Filan, Egan, and Feehily were in a six-member vocal group named IOU, which put out a single called "Together Girl Forever". They were then discovered by Louis Walsh (who was contacted by Filan's mother), the manager of 1990s boy band Boyzone, but did not meet Simon Cowell's approval for a record deal with BMG, so changes were needed. The other three members of IOU were given the sack, and Walsh went to Dublin and recruited Byrne and McFadden. The new group was named Westside. That conflicted with another band of the same name so their name was changed to Westlife. Boyzone singer Ronan Keating was brought in to co-manage the band with Walsh.
Their first single "Swear It Again" was released in April 1999, going straight to the top of the charts in Ireland and the UK.
Filan is the group's de facto lead singer, using a commercial pop style, and does some songwriting. Egan is a multi-instrumentalist who has a distinctive rock voice. Byrne is known for his husky voice, Feehily has a soulful voice, and McFadden supplies a plaintive voice. As well as singing, all the boys as well as Filan write songs as well. While Boyzone is an obvious antecedant, Westlife's ballad-heavy style also owes a debt to Boyz II Men.
Although the band has enjoyed unprecedented success in the Irish singles chart, many detractors argue it has been achieved by releasing bland unmemorable ballads and cover versions into a declining singles market.
As of late 2005, they have published five original pop albums, one greatest hits album and one Frank Sinatra-inspired swing album. Westlife's fan base is global: they have had success all over the world, especially Scandinavia and South East Asia, but also elsewhere in Europe, Canada, Latin America, South Africa and Australia. Westlife have had record-selling indoor arena tours and are one of the biggest pop acts to come out of Ireland.
Westlife have not managed success in the United States, though. Their debut single and music video "Swear It Again" was released in the US in Summer 2000 and was a minor hit on mainstream radio and MTV, reaching number 20 on the Billboard Hot 100 and being shown briefly on MTV's Total Request Live. Their debut American album was also released in 2000, but they have not released another one there since. The original Westlife hit most known to American audiences is "Flying Without Wings", since it was later a success for American Idol winner Ruben Studdard. Westlife would also collaborate with Asian-music sensation, BoA, on a Korean language version of the song which would appear on her mini-album, Shine We Are!
The band won ITV's Record of the Year competition on a record four occasions, with "Flying Without Wings", "My Love", "Mandy" and "You Raise Me Up".
Bryan McFadden left the band on 9 March 2004 to devote more of his time to his family life with the British TV personality and former Atomic Kitten member Kerry Katona, although he has subsequently separated from her and reverted the spelling of his first name back to its original 'Brian'.
Like most other boy bands, Westlife is primarily marketed to teenage girls, but they also have a large following of male fans and have performed numerous times at gay venues in the UK. On 19 August 2005, Mark Feehily put to rest years of speculation among fans that he was gay by publicly coming out of the closet in the UK tabloid The Sun, and announced his relationship with Kevin McDaid of the former boy band V.
Westlife's seventh full-length album, Face to Face, was released in October 2005. On 6 November 2005, the album and the single, a cover of the Secret Garden song "You Raise Me Up" reached number one on the UK charts, marking the first time the group held both top album and single in the same week. Having outlasted just about every other boy band, the members of Westlife continue to laugh off any speculation of a split-up, claiming their goal is to score at least 20 UK number one singles.
In February 2006, the band won three Naomi Awards for Worst International Album (Face to Face), Worst International Group and Outstandingly Bad Contribution to Music.