Mum-of-one Frankie, who married footballer Wayne Bridge last month, broke the news while appearing on BBC Breakfast this morning with her bandmates.
"I'm such a huge fan of Strictly! I've always wanted to be a part of the show," said the 25-year-old. "It looks like so much fun and the costumes are just gorgeous."
Despite having plenty of dancing experience, it seems Frankie is still nervous about learning new styles of dance.
She added: "Like so many little girls, I used to take dance lessons when I was in primary school and I really love dancing but this is going to be so different from anything I have done with The Saturdays. I just can't wait to get started!"
Frankie shot to fame at the age of 12 with the young pop group S Club Juniors, and in 2007 she successfully auditioned for The Saturdays.
The girl group have gone on to achieve four top ten albums and 13 top ten singles.
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