The dramatisation of the true-life relationship between King George VI and his speech therapist won seven awards at the ceremony held in central London's Royal Opera House.
A selection of Hollywood royalty including Samuel L. Jackson and Mickey Rourke looked on as the story of the stuttering sovereign beat off competition from "The Social Network," "Black Swan," Inception" and "True Grit".
The film is among the favourites to collect the Best Picture award at the Oscars on February 27.
Firth has now claimed the impressive double of BAFTA and Golden Globe for his portrayal of Queen Elizabeth II's father, but will have to wait two weeks to find out if he can complete the set with the biggest prize in showbusiness.
The 50-year-old actor used his speech to reveal the circumstances of his first meeting with director Tom Hooper.
"I had to postpone a routine but somewhat uncomfortable medical examination," Firth recalled.
"I am happy to report that the meeting was rather less uncomfortable than the exam, but as time went on it became clear that Tom's working methods were just as thorough and invasive as my doctor's.
"But when you see the results you're grateful, so I am thankful as I am to my doctor," the "Bridget Jones's Diary" actor added.
The Queen was reported to have given the royal seal approval to the triumphant film, an endorsement which Firth admitted meant "a very great deal."
Hooper said he was "completely thrilled" by the film's raft of awards.
Helena Bonham Carter earlier won best Supporting Actress for her portrayal of the king's wife.
"I'm so used to losing that it's kind of a strange feeling to win," said Bonham Carter in her acceptance speech.
"It's very nice, but children, if you're watching, it's not about the winning. It still feels nice."
Geoffrey Rush walked off with best Supporting Actor for his role as the king's speech therapist.
Decades before her death, the Queen's mother told the film's writer, David Seidler, that she approved of him recounting the story once she had passed away.
"She was a lovely old lady and I thought a couple of years, three at the most, but 25 years later I was able to make the film," Seidler said.
Natalie Portman was unable to collect the Best Actress award for her performance in "Black Swan" due to her pregnancy. The trophy was picked up by the film's director, Darren Aronofsky.
"She trained for a year before we made this movie," Aronofsky told the audience.
"When we shot every day she was in every single scene and every single shot. So with a lot of pride I thank you for this for her. Thank you Natalie."
West Wing creator Aaron Sorkin scooped the Adapted Screenplay prize for The Social Network, a film tracing the rise of social networking website Facebook. "Under normal circumstances I would be very excited about this but sitting in the seat in front of me is one of The Beatles," Sorkin said, referring to fellow guest Paul McCartney.
Veteran star Christopher Lee was presented with the Fellowship award by US director Tim Burton.
"This is a truly great honour, a great, great honour," the 88-year-old actor said.
"Two things really make it so. The fact that this was voted to me by my peers and secondly that I received it from one of the great directors of our age." (AFP)