It won four gongs in total and is favourite to pick up the Best Picture award at the Oscars later this month.
Costume romp "The Favourite" was the biggest victor at the BAFTAs on Sunday, taking seven awards, but Netflix black and white film "Roma" picked up the Best Film prize, as well as Director, at Britain's top movie honors.
Roma also won Best Cinematography, Best Foreign Language Film and Best Director for Alfonso Cuaron.
Addressing the other winners from The Favourite, she said: "We are having an awesome night aren't we?" Colman said. "We're going to get so pissed (drunk) later".
"If they do good movies, they should be recognised".
"The thing I really want to do is, Emma and Rachel (must keep this together) not just for your performances but for what you did after the cameras stopped rolling".
"As far as I'm concerned, all three of us are the same and should be the lead".
British actress Olivia Colman poses with the award for a Leading Actress for her work on the film "The Favourite" at the BAFTA at the Royal Albert Hall in London, February 10, 2019. It's got my name on it but we can scratch in some others.
Rachel Weisz had earlier picked up the prize for Best Supporting Actress for her role as the Duchess Of Malborough, while it also scooped the award for Outstanding British Film.
A Star Is Born won for its original music, with the film's writer, director, star and composer Bradley Cooper collecting the prize.
Rami Malek's portrayal of the late Queen frontman Freddie Mercury - a victim of the AIDS epidemic in the days when homosexuality was taboo in rock-and-roll - earned him the best actor award, however. He paid tribute to his co-star, Lady Gaga, who was attending the Grammys in LA, which were taking place on the same night. The Duke of Cambridge as President of BAFTA presented the Fellowship of the Academy, its most prestigious honour, to film editor Thelma Schoonmaker.
The animation category was won by Spider-Man: Into The Spider-Verse, while Free Solo, a film about the first person to climb El Capitan in Yosemite National Park without ropes, was named best documentary.