The clip was played during The X Factor advert break on ITV on Sunday, with a black screen, some lyrics in white text and a voice appearing to be the singing sensation.
Adele's voice could be heard singing the words: "Hello, it's me. I was wondering if after all these years you'd like to meet to go over everything.
"They say that time's supposed to heal you, but I ain't done much healing."
The moment marked almost five years since her last chart-topping album, 21, which came out in January 2011. Adele's last single was her 2012 hit, 'Skyfall'.
Social media, particularly Twitter, erupted with excitement at the prospect of some highly-anticipated new music from Adele.
From fans to celebrities, check out some of the reactions below:
Adele .. I've missed you— ♕DinahJane (@dinahjane97) October 18, 2015
I've listened to the snippet of Adele's new single more than I've listened to any ex's voicemails post-breakup.— Alex Goldschmidt (@alexandergold) October 19, 2015
No name, no face, just one unmistakable voice. Only Adele! Omg she's back!! pic.twitter.com/18H9l7xoPk— Jocas de Leon (@jocasdeleon) October 18, 2015
Adele :)— OneRepublic (@OneRepublic) October 18, 2015
my pal ran out of the toilet thinking it was a really good X Factor contestant. #Adele— nick grimshaw (@grimmers) October 18, 2015
Oh my word that Adele promo was UNBELIEVABLE. What a woman. #xfactor— IncrediblyRich (@IncrediblyRich) October 18, 2015
I am beyond excited for @OfficialAdele 's new album eeeeeeeeeeeeeee— Pixie Lott (@PixieLott) October 17, 2015
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