What else have they achieved?
Well, they've released five albums and sold a whopping 30 million records. Add to that numerous awards, including several for "record of the year".
Did anything change in their personal lives?
Well, three of the five lads got wed. Bryan married I'm A Celeb star Kerry McFadden in 2002. They have two daughters.
Last summer, Nicky tied the knot with Georgina Ahern - daughter of the Irish Prime Minister. And in December , Shane married Gillian Walsh, who happens to be Kian's cousin.
Kian has been dating Hollyoaks actress Jodi Albert, so that leaves Mark as the only official singleton in the band.
How long have the split rumours been going on for?
Ages. Way back in 2002, the boys told Newsround they weren't splitting up after the departure of their tour manager started rumours of a break-up.
The release of their greatest hits album last year sparked a fresh round of gossip.
Now, it's official. There is no split. It's just that Westlife will be a four-piece instead of a five-piece, because Bryan's leaving to spend more time with his family.
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