The critically-acclaimed film won its three leading stars the main acting prizes - Colin Firth was named Best Actor for his role as stuttering British monarch George VI; Helena Bonham Carter took home the Best Supporting Actress title, while the Best Supporting Actor award went to Geoffrey Rush.
The movie picked up the coveted Best Film honour, beating fellow contenders Black Swan, Inception, The Social Network and True Grit.
It also won the Outstanding British Film, Best Score and Best Original Screenplay awards.
Firth, who also claimed the Best Actor trophy last year (10) for his role in A Single Man, said, "I like coming here, thank you BAFTA." He also thanked his family for "remaining so steady whether they are dealing with a dancing queen or a sometime king".
Natalie Portman was the night's leading lady, collecting the Best Actress honour for her disturbing role in ballet thriller Black Swan. The pregnant star did not attend the ceremony and her trophy was accepted by director Darren Aronofsky.
The Best Director prize was awarded to David Fincher for The Social Network with the film's stars, Jesse Eisenberg and Andrew Garfield, accepting it on his behalf.
British actor Tom Hardy received high praise from film fans who voted him the winner of the event's Rising Star Award, seeing off competition from new Spider-Man Andrew Garfield, Gemma Arterton and Aaron Johnson.
Toy Story 3 continued its successful run by winning another prize in the Best Animated Movie category, while Inception took the award for Special Visual Effects. The movie also claimed an accolade for Production Design.
Harry Potter creator J.K. Rowling and stars Emma Watson and Rupert Grint took to the stage to accept a special honour for Outstanding British Contribution to Cinema, while Hammer Horror legend Sir Christoper Lee received a British Academy of Film and Television Arts (BAFTA) Academy Fellowship.
The main 2011 BAFTA winners are:
Best Film - The King's Speech
Leading Actor - Colin Firth (The King's Speech)
Leading Actress - Natalie Portman (Black Swan)
Supporting Actor - Geoffrey Rush (The King's Speech)
Supporting Actress - Helena Bonham Carter (The King's Speech)
Director - David Fincher (The Social Network)
Outstanding British Film - The King's Speech
Original Screenplay - The King's Speech
Adapted Screenplay - The Social Network
Special Visual Effects - Toy Story 3
Animated Film - Toy Story 3
Orange Wednesdays Rising Star Award - Tom Hardy.