The 'Flying Without Wings' hitmakers - comprised of Kian Egan, Nicky Byrne, Mark Feehily and Shane Filan - have recorded a new album and will head out on a 20th anniversary arena tour of the UK, as well as playing a homecoming show at Croke Park stadium in Dublin, Ireland, next year.
The boys teamed up with Ed Sheeran and his regular co-writer Steve Mac on their forthcoming comeback single and they believe the move will help them achieve their goal of recreating the success they had in the 90s, just like the 'Never Forget' hitmakers did with their revival as a three-piece - consisting of Gary Barlow, Mark Owen and Howard Donald.
Nicky said: ''We've got a five-year plan.''
Insisting their reunion isn't about the money, Shane told The Sun newspaper's Bizarre column: ''If it was just for the money, the option to tour and make a load of cash was always going to be there but we all sat down and agreed we just didn't want to do that.
''We wanted to go and do new music, and honestly the two people who could make it happen were Steve Mac and Ed Sheeran.
''We thought, 'If we can get them, we hear they might be interested, then this is the way to take Westlife on, the way Take That came back.
''They were nearly better the second time round than they were the first. And that's where our ambition is.''
On their biggest rival, Take That - which also included Robbie Williams and Jason Orange - Shane added: ''It's a bit like sport -- you look at your rivals, and we looked at Take That, who came back with 'Shine', 'Greatest Day', 'Rule The World', 'Patience'. It was unbelievable, and we have to see that as a benchmark -- but obviously getting Ed and Steve on board gives us the best chance of that.''
Nicky - who has sons Rocco and Jay and daughter Gia with his wife Georgina - says his kids are thrilled that their dad's band has recruited a pop artist to write their single as they aren't fans of Westlife's old stuff.
He quipped: ''My kids said to me, 'Dad, if you're doing this reunion you're not doing all those crap songs you did the first time!'
''And I said, thinking, 'Jesus, that's a bit harsh', I said, 'Lads, Ed Sheeran's written it' and they were blown away -- so it's finally made me cool to them too.''
Westlife's tour is aptly titled 'The Twenty Tour' and kicks off on May 25 at Belfast's SSE Arena, before concluding at Dublin's Croke Park on July 5.
Tickets for go on-sale to the general public on October 25 at 9am at www.livenation.co.uk
Westlife's 'The Twenty Tour' date are as follows:
Saturday, May 25, Belfast SSE Arena
Sunday, May 26, Belfast SSE Arena
Thursday, May 30, Manchester Arena
Friday, May 31, Newcastle Metro Radio Arena
Monday, June 3, Glasgow The SSE Hydro
Friday, June 7, Sheffield Fly DSA Arena
Monday, June 10, Leeds First Direct Arena
Thursday, June 13, London The O2
Tuesday, June 18, Nottingham Motorpoint Arena
Friday, June 21, Birmingham Arena
Tuesday, June 25, Liverpool Echo Arena
Friday, July 5, Dublin Croke Park
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