King's Speech, The (2010) has been crowned best picture at the Oscars, with star Colin Firth named best actor.
Tom Hooper was named best director for the film, which also won for best original screenplay at the ceremony.
Its best picture rival, The Social Network, won for adapted screenplay, film editing and score. Natalie Portman won best actress for Black Swan.
Briton Christian Bale and Melissa Leo won supporting acting awards for boxing drama The Fighter.
Firth, who had been firm favourite to win for his portrayal of King George VI battling a stammer, joked: "I have a feeling my career's just peaked."
The success of The King's Speech denied director David Fincher and his film The Social Network, the story of the creation of Facebook that was considered its closest rival at the ceremony in Los Angeles' Kodak Theatre.
Paying tribute to his film's stars, Hooper said: "Thank you to my wonderful actors, the triangle of man-love which is Colin Firth, Geoffrey Rush and me. I'm only here because of you guys."
Screenwriter David Seidler thanked the Queen for "not putting me in the Tower of London" for the swearing that featured in his Oscar-winning script.
The King's Speech had led the nominations, competing in 12 categories, ahead of the 10 nominations for True Grit - from which the Coen brothers' Western won nothing.
There had been eight nominations each for Inception and The Social Network, the adapted screenplay for the latter winning an Oscar for The West Wing creator Aaron Sorkin.
Portman had been the favourite for the best actress prize for her performance as a disturbed ballet dancer in Black Swan.
"This is insane, and I truly, sincerely wish that the prize tonight was to get to work with my fellow nominees - I'm so in awe of you," said the pregnant actress.
Among the women she beat to the Oscar was The Kids Are All Right actress Annette Bening, who has now been nominated four times without success.
Best Motion Picture of the Year WINNER
: The King's Speech (2010): Iain Canning, Emile Sherman, Gareth Unwin
Best Performance by an Actor in a Leading Role WINNER
: Colin Firth for The King's Speech (2010)
Best Performance by an Actress in a Leading Role WINNER
: Natalie Portman for Black Swan (2010)
Best Performance by an Actor in a Supporting Role WINNER
: Christian Bale for The Fighter (2010)
Best Performance by an Actress in a Supporting Role WINNER
: Melissa Leo for The Fighter (2010)
Best Achievement in Directing WINNER
: Tom Hooper for The King's Speech (2010)
Best Writing, Screenplay Written Directly for the Screen WINNER
: The King's Speech (2010): David Seidler
Best Writing, Screenplay Based on Material Previously Produced or Published WINNER
: The Social Network (2010): Aaron Sorkin
Best Animated Feature Film of the Year WINNER
: Toy Story 3 (2010): Lee Unkrich
Best Foreign Language Film of the Year WINNER
: Civilization (2010): Susanne Bier(Denmark)
Best Achievement in Cinematography WINNER
: Inception (2010): Wally Pfister
Best Achievement in Editing WINNER
: The Social Network (2010): Kirk Baxter, Angus Wall
Best Achievement in Art Direction WINNER
: Alice in Wonderland (2010): Robert Stromberg, Karen O'Hara
Best Achievement in Costume Design WINNER
: Alice in Wonderland (2010): Colleen Atwood
Best Achievement in Makeup WINNER
: The Wolfman (2010): Rick Baker, Dave Elsey
Best Achievement in Music Written for Motion Pictures, Original Score WINNER
: The Social Network (2010): Trent Reznor, Atticus Ross
Best Achievement in Music Written for Motion Pictures, Original Song WINNER
: Toy Story 3 (2010): Randy Newman("We Belong Together"
Best Achievement in Sound Mixing WINNER
: Inception (2010): Lora Hirschberg, Gary Rizzo, Ed Novick
Best Achievement in Sound Editing WINNER
: Inception (2010): Richard King
Best Achievement in Visual Effects WINNER
: Inception (2010): Chris Corbould, Andrew Lockley, Pete Bebb, Paul J. Franklin
Best Documentary, Features WINNER
: Inside Job (2010): Charles Ferguson, Audrey Marrs
Best Documentary, Short Subjects WINNER
: Strangers No More (2010): Karen Goodman, Kirk Simon
Best Short Film, Animated WINNER
: The Lost Thing (2010): Shaun Tan, Andrew Ruhemann
Best Short Film, Live Action WINNER
: God of Love (2010): Luke Matheny
Source: Press Release