The movie about King George VI's stammer won best ensemble prize and best actor for Colin Firth at the Screen Actors Guild (SAG) awards, while Natalie Portman won best actress for her role in ballet-themed thriller "Black Swan."
The awards for Firth and Portman are their latest for those roles, and seem to cement them as frontrunners for best actor and actress Oscars.
Others honored at the SAG awards -- chosen by actors for their peers -- included Briton Christian Bale for best supporting actor and Melissa Leo for best supporting actress, both in boxing movie "The Fighter."
The latest triumph for "The King's Speech" came a day after its director Tom Hooper won best director at the Directors Guild of America (DGA) awards on Saturday night.
The understated royal movie, also starring Helena Bonham Carter and Australian Geoffrey Rush -- is nominated in 12 categories for next month's Oscars show, the climax of Hollywood's annual awards season.
Blockbuster Facebook movie "The Social Network" was an early favorite for Oscars glory, and came out on top at the Golden Globes earlier this month, taking four prizes to a disappointing single gong for "The King's Speech."
But insiders point out that the Globes are chosen by a few dozen foreign journalists at the Hollywood Foreign Press Association (HFPA), whereas all other awards are voted on by those in the industry.
The Oscars, chosen by some 6,000 members of the illustrious Academy of Motion Picture Arts and Sciences, will unveil their laureates this year on February 27.
Firth, accepting his SAG award Sunday, underlined the value he attached to being honored by his fellow actors.
"Until today, I would say probably if ever I felt I had a trophy which told me that something's really happening for me, it was my SAG card, you know, to be a part of this extraordinary collective," said Firth, accepting his award.
"Growing up in England, it's not something you expect to see in your wallet, really," he said. "And so it has this glow, and I used to flash it around hoping it would get me female attention, entry into nightclubs..."
"And it didn't, not a bit. I'd like to thank, looking at whose here, I'd like to thank security for letting me into the building," he joked.
