Sci-fi thriller Inception and Facebook movie The Social Network took away the top prizes at the Writers Guild of America (WGA) awards.
Inception, which stars Leonardo DiCaprio, won best original screenplay, while The Social Network was named best-adapted screenplay, reports the BBC.
The King's Speech, which is nominated for 12 Oscars, was ineligible for the awards and did not make the shortlist.Winners were announced at simultaneous ceremonies in New York and Los Angeles.
British-born filmmaker Christopher Nolan, who wrote, produced and directed the film, called the award an "incredible honour".
The Royal drama is in the running for the best original screenplay Oscar, against Nolan's film.
It was ruled out of contention for the WGA awards because it was not produced under contractual guidance issued by the union.
"I wrote a good screenplay, but [director] David Fincher made a great movie," Social Network writer Aaron Sorkin said.
The writers of Mad Men were honoured for best television drama, with Boardwalk Empire collecting the award for outstanding new TV drama.
British screenwriter Peter Morgan, whose previous credits include The Queen and Frost/Nixon, was awarded for his work on small screen drama The Special Relationship.