She was right in the middle of giving an emotional acceptance speech about how she was proud to be flying the flag for Britain.
So when she was interrupted so Brit Awards host James Corden could introduce Blur, Adele didn't take too kindly.
The singer, who had won the top award of the night, Album of the Year, flipped the middle finger to show just how annoyed she was.
Adele, who earlier performed a stunning rendition of Rolling In The Deep, said afterwards it was "to all the suits" of the show.
The 23-year-old was on stage accepting her second award of the night — after taking home Best Female Artist — presented by George Michael.
She said: "Thank you so much, thank you, thank you very, very much.
"Nothing beats coming home with six Grammys and then coming to the Brits and winning album of the year.
"I'm so proud to be flying the British flag for all of you."
James then appeared on stage, met by boos from the crowd, and said: "I'm so sorry, can I just cut off?"
Adele said: "Are you about to cut me off? Can I just say then, goodbye and I'll see you next time round."
She then proceeded to flip the bird, amid cheers from the audience.
The star said afterwards: "I was about to thank the British public for their support. They cut me off, sorry if I offended anyone but the suits offended me."
She added: "I got cut off during my speech and flung the middle finger. But that finger was to the suits at the Brit Awards, not to my fans."
