The 23-year-old Scottish singer was the big winner of the night, scooping both New Artist of the Year and Song of the Year for Someone You Loved.
Accepting the New Artist award Capaldi swigged from a bottle of beer before simply saying, “Thank you very f***ing much.”
Due to his use of an expletive the entire speech was muted for those watching the ceremony live on ITV.
Taking to the stage later in the evening to receive the song award Capaldi - whose ex-girlfriend Paige Turley is currently starring ITV2 dating show Love Island said: “Contrary to popular belief, a lot of people think this song is about my ex-girlfriend who is now on Love Island. Actually it’s about my grandmother who sadly passed away a few years ago.
Read more: Brits 2020 winners in full
“I hope to God ITV don’t contact her to be on a reality show!”
He said thank you for the award, adding: “Thanks to my mum and dad for making love. Thanks to my grandmother for... dying!”
Billie Eilish broke down in tears as she accepted the award for International Female Solo Artist.
The 18-year-old No Time To Die singer told the audience:“I have felt very hated recently. When I was on the stage and saw you guys smiling at me, it genuinely made me want to cry. I want to cry right now.”
She then burst into tears and was comforted by Spice Girl Mel C, who had presented her with the award.
The other big winners of the night were rapper Dave who scooped Album of the Year, following an incredible performance of his song Black, in which he addressed racism in Britain, calling Prime Minister Boris Johnson “a real racist”.
Stormzy also gave an amazing performance of his hits Don't Forget to Breathe and Do Better, starting out alone on a stool before the lights came up to reveal an enormous choir filling the stage.
The grime star won Best Male Solo Artist, and thanked all the “incredible females” who had helped him, after the Brit Awards were criticised for a lack of female nominees.
And the late TV presenter Caroline Flack - who it emerged at the weekend had taken her own life aged just 40 - was remembered at the ceremony.
Host Jack Whitehall paid tribute to Flack, while her ex-boyfriend Harry Styles wore a black ribbon and a badge with a message about kindness in tribute to her.
The show closed with Sir Rod Stewart leading the entire room in a singalong of his hit I Don’t Want To Talk About It, before inviting former Faces bandmates Ronnie Wood and Kenney Jones on stage to rock out.