"We'll see each other in Australia in February," Mel B told the crowd. The details of Australia's concert dates – which would be the first time the group occurs in the country – have not yet been formally announced.
Geri Horner, aka Ginger Spice, also surprised the crowd Saturday apologizing for leaving the group in 1998.
"I have to say something that I should have said a long time ago," Geri told 70,000 loyal fans at Wembley Stadium.
"I'm sorry, I'm sorry to be gone – I was just a kid – it's so good to be back with the girls I love."
Geri left the group in 1998 after apparently suffering from health problems, two years before the whole group took an indefinite break.
His emotional announcement took place at the end of the band's 13-year group tour, and allowed singers to travel to cities such as Dublin, Cardiff, Manchester, Coventry, Sunderland, Edinburgh and Bristol.
Geri also shared a heartfelt video of herself standing inside the empty stadium after the last show. "That's it, they're taking it, it's amazing," she said, shrugging her shoulders.
She posted another video thanking her colleagues from the group and everyone who attended the concerts. "Thirteen stadiums, about 70,000 people, with three amazing women with whom I shared this step," she said.
"I want to thank Melanie, Melanie and Emma and all the people who have come forward for us.This is something I will never forget.Thank you very much.Great love to Spice World."
A number of distinguished guests attended the Saturday night concert, including singer Adele, winner of a Grammy Award.
"The last time I saw the Spice Girls at Wembley, it was 21 years ago," she wrote on Instagram. "Tonight with my loved ones, I cried, laughed, screamed, danced, remembered and fell in love with my 10 year old self.
"It's no secret how much I love them, how much they inspired me to run to save my life and never look back." I finally met Ginger I got drunk with the girls and, frankly, I can not believe how much I'm coming. "
The Spice Girls began their reunion tour in May in Dublin. They occurred in four parts, Victoria Beckham, aka Posh Spice, having refused to participate.