"Oiii last time I saw the Spice Girls at Wembley was 21 years ago! Tonight with my nearest and dearest I cried, laughed, screamed, danced, reminisced and fell back in love with my 10 year old self," Adele captioned a slideshow of herself at the Wembley Stadium gig.
"It’s no secret how much I love them, how much they inspired me to run for my life and never look back," she continued.
"I finally got to meet Ginger, I got drunk with the girls and quite frankly I can’t believe how far I’ve come 😂 thank you for the madness I get to live, I couldn’t have got here without you 5 BRITISH legends! I love you! ❤️"
And the love went both ways, with the Spice Girls sharing a snap of them with superfan Adele posing front and centre, surrounded by Emma Bunton, Geri Halliwell, Mel Brown and Melanie Chisholm.
Emma Bunton also shared a photo to her Instagram, writing: "Selfie with @adele gorgeous lady!"
And Geri (now Geri Horner) reposted Adele's slideshow, captioning the post: "We love you @adele ❤️🇬🇧 @spicegirls"
Proving her superfan status, Adele posted a tribute to the girl group back in November when they first announced their reunion tour.
"HA! This is how I feel right now! I AM READY ✌🏻," Adele captioned a throwback pic of herself as a kid, surrounded by posters of her idols.
The Spice Girls were performing as part of their reunion tour, which has seen Baby Spice, Ginger Spice, Scary Spice and Sporty reunite on stage for the first time in six years - Posh Spice Victoria Beckham was the only member of the band not to come back for the concerts.
She last performed when the group reunited to close the London Olympics in 2012.
Mel B delighted Australian fans by announcing the Spice Girls will bring their tour to Australia next year.
“We’ll see you in February in Australia!” she declared after Saturday's night's concert.
Details about the Spice Girls tour, which will be the first time they’ve ever played a concert in Australia, have not yet been announced.