The news was revealed on Monday (7 August) on Nick Grimshaw’s Radio 1 Breakfast Show.
Speaking live on the programme, Mollie said: ”I’m so excited that I can actually talk to people about it.
“I’ve known for quite a while and I’m so bad at keeping secrets like this, so i keep slipping up.”
The singer admitted she had already told her parents and two sisters, along with her former bandmate Frankie Bridge, who previously competed on the show.
She also said in a statement released on the ‘Strictly’ press team’s Twitter account: “I’m a huge fan of ‘Strictly Come Dancing’ so I can’t actually believe I’m lucky enough to be taking part in it this year!
“I’m literally so excited to learn Latin and ballroom dancing, and of course I can’t wait to get into the sequins too!
“It’s going to be a lot of hard work but I’m ready for the challenge.”
The rest of the line-up will be revealed in the coming weeks and so far, reports have claimed we could see stars including Joe Wicks, singer Matt Goss, Paralympic swimmer Ellie Simmonds and ‘Gogglebox’ faves Steph and Dom Parker getting their dancing shoes on.