Mika, who scooped the award for best British breakthrough artist, opened the Brit Awards with two of his songs and a duet with Gossip singer Beth Ditto.
The Arctic Monkeys sported tweed waistcoats and caps. They were named British group of the year and also took best British album for Favourite Worst Nightmare.
Mark Ronson, who produced Amy Winehouse's last album, performed with the singer at the show. It was her first public appearance since going into rehab.
Producer Mark Ronson is thought to be the first non-singing performer to win the best male solo award.
Take That were among the big winners. Their song Shine won the best single award, which was chosen during a live phone vote during the show.
Sir Paul McCartney was presented with the outstanding contribution to music award before performing a medley of his hits, including Live and Let Die and Hey Jude.
Adele, whose debut album 19 recently went to number one, picked up the Critics' Choice Award at the ceremony.
X Factor winner Leona Lewis, who performed her hit Bleeding Love, failed to scoop any awards, despite being nominated for four.
Kylie Minogue, winner of best international female, was one of the first artists to arrive for the awards at London's Earl Court.
The Osbourne family hosted the show. Will Young, Kelly Rowland and David Tennant were just some of the stars who presented awards.
Pop act Girls Aloud, minus Nadine Coyle, missed out on winning their first Brit Award. They lost out to the Arctic Monkeys in the British group category.