To remind us of their career highlights - spanning 14 years and ten albums - the group have handily put out their final Greatest Hits LP this week.
With the retrospective riding high in the charts, we phoned up Nicky Byrne to find out what he plans to do post-split and whether the group are already considering a future reunion.
Is this really the end of Westlife or are you already thinking ahead to your reunion?
"It genuinely is the end! I mean, you can never say never - and it will be nice to see the boys again down the line. We've still got our tour, and we're really looking forward to going out with a bang. Louis [Walsh] wanted us to take a two-year sabbatical and come back to it, but that would have been too watered down for us. We needed to get away from it - we've given it our all during these 14 years."
It doesn't seem like you've ever had much of a break in those 14 years...
"We took four or five months off after our album Allow Us To Be Frank. It was a bad time in the band - Brian [McFadden] had left, we came out with a rat-pack album, the tour didn't do great and we had one album left on our contract. I actually went and did an acting course in New York to prepare me for what might happen next. We came back and recorded what we all thought might be our last hurrah - songs like 'You Raise Me Up' - and it ended up being huge, so we stuck with it a while longer. It's a miracle and a blessing that we lasted 14 years."
What do you think the secret is to a long-lasting boyband?
"There's no one-line answer to that, but one of the huge things that helps is being really honest with each other from the beginning. If someone was offered a solo deal, the rest of us would want to know about it because it affects our lives too. We all kept our cards on the table as much as we could. I think we were also blessed have Simon Cowell and Louis Walsh, who were a great team at the time we got them. The late '90s were also a great time to launch in the music industry."
What is Louis going to do now? He also threatened to leave The X Factor...
"He's been in the music industry for a long time - he'll be fine! There's life in the old dog yet. He's worked with Boyzone, Jedward, Girls Aloud and JLS for a short time. There's still room for him to do something again. What's going on with the panel on this year's show is not brilliant. There's no man better that Simon for sorting it out - I wouldn't be surprised if we see Simon, Louis, Cheryl and Dannii back year."
What are your plans after your farewell tour?
"I think TV and radio is something I really enjoy, and I've been dipping my toes into both over the years. I presented on BBC Radio 2 last week, which really gave me a buzz. It would be great to have a role like Ryan Seacrest. It's great to be able to have those discussions now without feeling guilty."
You've always had a hard time from critics; were you keen to go out on a high?
"We've had a lot of stick, but we've always been able to laugh at it. I've been on Digital Spy many times and laughed my tits off and things people are saying. We're obviously not going to be everybody's cup of tea, but you have to take it on the chin. When we first started we auditioned as if we were going to be the new Backstreet Boys, but Simon and Louis obviously saw a niche in the market and marketed us very differently.
People have often referred to you as a stool band...
"People joke about us being a stool band who always stood up for the big key change. Truth is, we were just as embarrassed by it! One thing no-one could take away from us was that we always sang the songs well. I understood why the average person thought we were a band who sang covers and sat on stools - we got that - but our fans who bought the albums and came to the shows would always see a lot more."
Is it true you were all big party-goers too?
"I never understood the whole boring side of Westlife. Maybe people thought that after seeing us on TV, but we were always having a laugh away from that. We recorded songs with some of the best artists in the world - I remember one amazing night out we had with the Backstreet Boys in Sweden. A lot of that stuff never got in the press, which in many ways was a good thing - we saw other boybands getting a hard time being photographed coming out of clubs. It was kind of cooler not to be there - you don't see the bigger artists going about town, do you?
"At the end of the day, we're a pop band, and at 32 years old we thought there had to be more out there than this. We're not a new face walking through the door anymore - we've been that, and it was amazing. We could have taken the money and stayed together for a few more years, but we all thought it was time to see what else is out there."
Westlife's Greatest Hits album is out now. Their farewell tour kicks off next year.
Watch the music video for their latest single 'Lighthouse' below: