The band took to the stage for the first time in 12 years as they performed a medley of their greatest hits - and Twitter was sent into meltdown!
Paul Cattermole, Jon Lee, Bradley McIntosh, Rachel Stevens, Tina Barrett, Hannah Spearitt and Jo O'Meara looked happy to be reunited on Friday night (14 November) as they sang hits including 'Bring It All Back', 'S Club Party' and 'Don't Stop Movin'.
Fans and non-fans alike couldn't helped but be caught up in the excitement as the Noughties band busted some moves all for a good cause.
The comeback was one of the most talked about events of this year's Children In Need, which also included a performance from Cheryl Fernandez-Versini and a special Grease medley from the EastEnders cast.
As Twitter went into overdrive, celebrities also joined in the commentary.
McFly's Harry Judd tweeted: "Don't stop movin' to the S club beat" #sclub7. I won't Rachel (Izzy says I'm allowed to still fancy her, win)."
Rylan Clark gushed: "Don't stop never give up hold your head high and reach the top let the world see what you have got bring it all back to you @SClub7."
While Strictly Come Dancing's professional dancer Robin Windsor wrote: "The @SClub7 reunion on @BBCCiN has just made me feel really old! But took me back to a FABULOUS time."
Surprisingly, acerbic comic Ricky Gervais also joined in the fun, saying: "There ain't no party like an S Club party."
The seven-piece confirmed they would be reuniting for the BBC's famous charity event in October, following months of speculation about a re-grouping.
After performing, Rachel Stevens also took to Twitter to express her excitement. Posting a picture of herself wearing a big smile, she wrote: "This smile says it all! So amazing to be back on stage together and the audience were amazing! Thanks 4 all the love! x."
S Club 7 - who split in 2003 - thanked fans with the message: "We couldn't have loved that more! Best fans in the world! #SCLUBPARTYTIME #sclub7 @BBCCiN."
Their greatest hits album is currently climbing up the charts again, and a tour is rumoured to be on the cards in 2015.
At the time of writing, Children In Need had raised a record-breaking £32.6 million.
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Watch S Club 7's Greatest Hits Medley on BBC Children In Need 2014:
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