They added: "The decision is entirely amicable and after spending all of our adult life together so far, we want to have a well-earned break and look at new ventures.
"We see the greatest hits collection and the farewell tour as the perfect way to celebrate our incredible career along with our fans. We are really looking forward to getting out on the tour and seeing our fans one last time."
They added that they have "countless memories that we will forever cherish".
The statement continued: "Over the years Westlife has become so much more to us than just a band.
"Westlife are a family. We would like to thank our fans who have been with us on this amazing journey and are part of our family too. It has been a dream come true for all of us."
It appeared Westlife - whose members are estimated to be worth £10 million each - were close to disbanding in March when they split with label boss Simon Cowell after 13 years.
Instead, they signed a one-year deal with RCA Records for their Greatest Hits album.
At the time, Byrne blamed CowellÕs interest in The X Factor for their decision to leave his Sony/BMG label.
He said: "We signed to Simon back in 1998 and he was brilliant, but then came the development of X Factor and American Idol. Simon became famous himself and his interests went that way rather than on Westlife. We almost felt a little bit unloved with Simon Cowell."
The band, who were originally managed by X Factor judge Louis Walsh, began as a five-piece, but Brian McFadden left in 2004 and lives in Australia, where he is a judge on Australia's Got Talent.
It is not known what the four band members, all from Sligo in the west of Ireland, have planned for the future but Egan is being lined up as a coach for the Irish version of the singing talent show The Voice.
- Daily Mail
