Sugababes singer Berrabah and ex-Girls Aloud star Harding will join other British celebrities, including Steps singer Ian 'H' Watkins, super-middleweight boxing champ Carl Froch, and veteran fitness guru Mr. Motivator in new Bbc show Tumble.
The contestants will train with professional gymnasts to perfect tricky routines they will then showcase on the programme before a viewers' vote decides who stays and who goes.
Harding says, "I'm really looking forward (to it), but also a little bit scared about all the training I'll be doing - but at least it beats going to the gym."
Tumble is scheduled to air later this year (14).
There's still no reunion planned though.