The 42-year-old singer was part of the girl band alongside Victoria Beckham, Mel B, Emma Bunton and Mel C. She is due to tie the knot with Formula One boss Christian Horner today, and she has apparently enlisted the help of her former bandmates' little ones to make the ceremony extra special.
As well as having her nine-year-old daughter Bluebell as part of the wedding party, Geri will apparently be joined by Mel B's little girl Madison and Emma's two children Beau and Tate.
"Geri wanted her wedding to be a family affair with her own immediate relatives and her Spice Girls family," an insider told British newspaper The Sun.
“The Spice Girls were an important part of her life and she’s over the moon that Mel and Emma’s children can play a part."
It's thought Victoria and Mel C would have been involved too, but they aren't able to make the wedding because of prior commitments.
Geri and her fiancé will exchange vows in church, with the star due to arrive in a racing car courtesy of Christian. According to the publication, she will arrive in a two-seat Formula One vehicle which will be driven by a professional.
Although what Geri will wear is a closely-guarded secret, apparently her bridesmaids are being dressed by Nicki Macfarlane - who also did the honours for Britain's Duchess of Cambridge when she tied the knot with Prince William.
Initially it was reported that Geri and Christian were marrying at Syon House in west London but The Sun now suggests the event is actually being held at The Woburn Estate in Bedfordshire, which is outside London.