They also announced that, in honour of their comeback, they'll be creating an Atomic Kitten perfume and writing new material. We've found ten facts you may not have known about the Liverpudlian girlband.
1. The band originally formed in 1997 with Liz McClarnon, Kerry Katona and a 15-year-old Heidi Range. Founding member Heidi left due to artistic differences before the band secured a record deal. She of course went on to be a member of the Sugababes.
2. The song 'Whole Again' is the fourth best-selling single in the UK by a girlband. It falls just behind 'Never Ever' by All Saints, and 'Wannabe' and '2 Become 1' by the Spice Girls.
3. Before discovering the name Atomic Kitten, the band were previously called Honeyheads. They changed their name in 1998 to Automatic Kitten but changed it again when they thought it was too long.
4. Jenny Frost, who replaced Kerry Katona, was previously in girlband Precious. Their song 'Say It Again' was the 1999 Eurovision song contest entry from the UK. They finished 12th with 38 points. Charlotte Nilsson from Sweden won with the song 'Take Me to Your Heaven'.
5. Liz McClarnon also tried out for Eurovision but wasn't as successful as her bandmate. She entered her song '(Don't It Make You) Happy' for the 2007 contest. Unfortunately for Liz, she lost out to Scooch with the song 'Flying the Flag (For You)', which came 23rd out of 24 countries.
6. Original member Kerry Katona had a difficult and well-publicised upbringing. She was placed in care from a young age and was brought up by four sets of foster parents before leaving school at 16 to become a lap dancer.
7. Before Kerry rejoined the group for The Big Reunion, she stated that she wouldn't want to take part in the band's reconciliation. Wonder what changed her mind?
8. Despite the connection of once-shared band members, the Sugababes and Atomic Kitten were known for their rivalry. Original Sugababe member Mutya Buena once slated the Kittens, saying: "They're wannabes and we're real. We all have the ability to have solo careers. They just don't. They said we looked like their arses and we should get jobs in Sainsbury's." Ooh, catty!
9. Kool and the Gang scouted out the band to sing an updated version of their track 'Ladies Night'. In honour of the collaboration, the band also named their album Ladies Night. It went to number five in the charts and was certified platinum.
10. Pop princess Kylie Minogue wrote the song 'Feels So Good' for their second album. She donated it to the band as a favour to her producer Rob Davis.
Watch Digital Spy interview Liberty X, B*Witched and 5ive for ITV2's Big Reunion below: