The band which consists of Duncan James, Simon Webbe, Anthony Costa and Lee Ryan – will perform a self-penned song, entitled I Can, at the contest.
A documentary looking at the recording of the song and their preparation for the event will be screened on BBC One in April.
Blue – were one of the most successful boy bands of the past decade, scoring three number one albums and singles in the UK as well as selling over 13 million albums across Europe.
Their biggest hits included All Rise, One Love and their chart-topping cover of Sorry Seems To Be The Hardest Word on which they duetted with the song’s composer Elton John.
They split up in 2005 to concentrate on their solo careers but announced they were reforming in 2009.
Duncan James was the first band member to comment, posting on his Twitter page on Saturday night shortly after the news was announced.
“It’s about time we took Eurovision seriously as we’re the only country in Europe that doesn’t,” he said. “Let’s try and change that, but we need your support!!” he said.
It is not the first time that members of Blue have had a brush with Eurovision.
Anthony Costa attempted to represent the UK as a solo artist in 2006, eventually finishing second to Daz Sampson in the TV selection show Making Your Mind Up.
Lee Ryan wrote Guardian Angel, the song which Andy Scott-Lee attempted to represent the UK with in 2005, while Duncan James was a judge on Your Country Needs You in 2009, the show which was eventually won by Jade Ewen.
Duncan also announced the votes of the UK’s jury during the 2009 competition in Moscow.
It is the first time since 1994 that the UK representative has been internally selected rather than being chosen by the public.
On that occasion, singer Frances Ruffelle was picked by the BBC and eventually finished 10th in Dublin with the song Lonely Symphony.
The UK is hoping for a better result this year after the 2010 entry, That Sounds Good To Me sung by Josh Dubovie, ended up in last place with just 10 points.
It was the third time in less than ten years that the UK had come last, following Jemini’s Cry Baby in 2003 and Andy Abraham’s song Even If in 2008.
In that time the UK has only scored a top ten placing twice – with Jessica Garlick, who finished joint third in 2002 with Come Back, and Jade Ewen, who came fifth in 2009 with the Andrew Lloyd Webber-composed It’s My Time.
However it remains one of the most successful Eurovision countries in history, winning five times and finishing in second place on no less than 15 occasions.
The 2010 contest was won by Germany’s Lena with the song Satellite.