Host Corden was told to end Adele's speech for winning the prestigious 'British Album' prize for 21, as Blur were due to perform.
After Adele thanked her fans and said she was "so, so proud to be British and flying our flag", the Gavin & Stacey star stepped in and said apologetically: "I am so sorry and I can't believe I'm about to cut you off. I'm so sorry."
> Brit Awards 2012 winners - in full
> Brit Awards 2012 - Live blog
The 'Rolling in the Deep' singer said: "Goodbye, and I'll see you next time round," before flipping her middle finger in the direction of those in charge of the broadcast.
She later clarified that she made the gesture at the Brit Award "suits" for cutting her off, and not at the crowd or Blur.
Speaking on ITV2's The Brits Backstage, Corden suggested that the incident ruined his evening.
When Keith Lemon asked about his general feelings after the ceremony, he replied: "I'm alright - I just feel bad about having to cut Adele off. I really don't understand quite why I was made to, but it's not a very nice way to end.
"I was having the best night of my life but then I had to cut Adele off before she had a chance to say thank you - she's the biggest star in the world."
The 33-year-old added: "I don't quite understand what happened - but I'm quite upset about it.
"Blur playing for 11 minutes and she gets to just say 'Thank you' once. Up until then, I thought we'd really [been terrific]."
Adele later explained: "I flung the middle finger. That was for the suits at the Brit Awards, not my fans. I'm sorry if I offended anyone but the suits offended me."
> Brit Awards 2012 in pictures
> Brits 2012 red carpet pictures
Watch Adele perform 'Rolling in the Deep' at the Brit Awards 2012 below:
Scroll through Digital Spy's gallery of the 2012 Brit Awards below: