After winning six awards at the December 2000 Smash Hits Poll Winners Party, the Irish hunks can rightly lay claim to the title of Britain's biggest pop acts - but where did it all start?
Who are the members of Westlife?
Original band members Shane Filan, Kian Egan and Mark Feehily were born and grew up in the windy Irish west coast town of Sligo. In 1998, after success on local TV, Boyzone's manager Louis Walsh snapped then up and landed them a support slot in Dublin with boy band stalwarts The Backstreet Boys.
For the gig the trio contracted two further singers, Dubliners Bryan McFadden and Nicky Byrne. Boyzone frontman Ronan Keating then stepped in to manage the band and help nurture its raw talent.
In April 1999, Westlife's first single, Swear It Again, stormed into the top of the UK charts and since then there's been no looking back .he boys held the Christmas 2000 number one spot with their version of Abba's hit I Have A Dream for four weeks.
They then outsold the Spice Girls three times over with their new album Coast To Coast in November 2001. Rumours of a feud sprang up when Bryan dismissed the Spices' album Forever saying: "I've heard it, but I thought all the songs sounded the same." Mel C retorted on TV that she thought the boys were "talentless".
At the start of 2001 pop's best-kept secret was revealed when Bryan announced that he was to wed former Atomic Kitten singer Kerry Katona. It later emerged that the couple were expecting a child together - baby girl Molly was born on August 31, 2001 and second daughter Lilly Sue followed on February 5, 2003.
The other boys have also maintained fairly high profile romances. Nicky married Irish prime minister's daughter Georgina Ahern in August 2003, and the pair have welcomed three children together. Kian meanwhile married actress and singer Jodi Albert in 2009 and much like Nicky, the happy couple have also welcomed three children together.
Shane married childhood sweetheart Gillian Walsh, who is the cousin of Kian, in 2009. The couple have three children, Nicole, 17, Patrick, 14, and Shane Jr, 13.
Mark came out as gay in 2005, revealing that he was in a relationship with photographer Kevin McDaid. The pair got engaged in 2010, but on 31 December 2011, Mark confirmed the pair had split. The singer has since entered into a relationship with Cailean O'Neill, and the pair welcomed daughter Layla, three, in October 2019.
On March 9, 2004 Westlife fans were left stunned after Bryan McFadden revealed that he was to leave the band, saying he wanted to spend more time with his wife Kerry and their two young children. His family break was short lived, however and in October 2004, he announced he and his reality TV star wife were splitting up. The rest of the group continued successfully as a four, before announcing their amicable split in October 2011.
The band didn't stay apart forever, as in 2018 it emerged that they were planning a reunion, although Bryan McFadden would not be involved. They released their first single Hello My Love to critical acclaim at the start of 2019, and it became a certified gold hit seven months later in the UK. The band released their 11th studio album, Spectrum, later in the year before heading on a global tour.
Westlife continue to make music , with their latest album, Wild Dreams, being released in 2021 after they signed on with Warner Music UK and East West Records.