Antony Costa has insisted there was "never any doubt" that Blue would reunite.
The band reformed in 2009 after a four-year hiatus and have recently been given a boost thanks to their appearance on TV show The Big Reunion, but the singer suggested it was always on the cards that they would work together again.
He said: "Never any doubt. We've always stayed friends and we always supported each other. The boys came and saw me when I was performing on the West End in Blood Brothers, I went to see Simon (Webbe) in Sister Act, Duncan (James) in Legally Blonde and Lee (Ryan) in his solo stuff as well.
"Ten years on, we got asked to do Eurovision and it just felt right. It was our 10-year anniversary. Now it's 10 years since we released our last studio album, so everything's fitting in."
Blue have a new single and album and are set to go on a UK tour.
Antony promised that fans would get to hear some of their old hits at the gigs.
He said: "Listen, if it weren't for the oldies, I wouldn't be sitting here talking to you now. You've got to be able to please the people that remember you from back in the day. I love performing the old songs such as One Love, All Rise and Fly By."
He said they are also very pleased with their new record, Roulette.
"It's a very grown-up album, it's very mature. It's experiences we've all had over the years when Blue were apart, and coming together to create an evolved Blue sound, while keeping the classic Blue sound too. We're really chuffed with it," said the 31-year-old.
:: Blue's new single Hurt Lovers is out now, with the album Roulette released on Monday, April 29. They are performing at London's Shepherd's Bush Empire on May 3, with further dates in October. For more information, visit www.officialblue.com.