Perrie and Jesy were a part of the four-member group Faux Pas, while Leigh-Anne and Jade were part of a three-piece called Orion.
Both bands failed to get through again, but the judges picked out the four girls - and Rhythmix were formed.
Before joining Little Mix and going on to achieve global domination after winning The X Factor in 2011, Leigh-Anne had just finished her A-Levels and was working as a waitress in Pizza Hut.
She has her own fashion blog, called Leigh Loves, on Tumblr, where she treats fans with pictures of the clothes she loves.
No, she doesn't have a biological twin but she does have an older sister!
Big sis Sairah reportedly signed up to be one of Love Island's reserves on the 2018 show but she's now loved up with her boyfriend Jigz.
The girls were the first group to ever win The X Factor, and have gone on to tour the world as well as achieve a Christmas Number One single with Cannonball.Just like her Little Mix band mates, Leigh-Anne is obsessed with dogs and shares a number of pooches with her boyfriend Andre.