The Spice Girl - who also judges 'America's Got Talent' - will join 'Dancing On Ice' baddie Jason Gardiner and Wayne Sleep on the panel.
The ITV show will see celebrity couples, including JLS star Oritse Williams and his girlfriend AJ Azari and Denise Welch and her husband Lincoln Townley, competing against each other in a live dance competition, hosted by Davina McCall.
The trio of judges will offer feedback on their performances and give individual 'his and hers' scores. These will be combined with the viewer vote and from week two, the couple at the bottom of the leader board will be sent home.
Meanwhile, host Davina has admitted she doesn't think she and her husband of 13 years Matthew Robertson, could take part in the show.
She told The Sun: "I know that if Matthew and I had tried to do this a year into our relationship it would have been very different to now.
"You have to devote a huge amount of time to this show because it's so intense. With our kids the ages they are [two daughters aged 11 and nine and a son aged six] I don't think I could have found time to do it.
"Can I dance? I think I'm amazing but the correct answer would probably be no."
Laurence Llewelyn-Bowen and wife Jackie, Brian McFadden and Vogue Williams, 'Dempsey And Makepeace' stars Michael Brandon and Glynis Barber and boxing champion Carl Froch and partner Rachael Cordingley are also taking part in 'Stepping Out', which starts this Saturday.