The film, which revolves around CIA's attempt to free six US diplomats during the 1979 Iranian hostage crisis, is critics favourite to win some major trophies at the upcoming Oscars where it has seven nominations. 'Argo' has already won two Golden Globes.
"I'm really amazed and stunned," Affleck said while accepting the trophy.
Lawrence was named outstanding film actress for her performance in 'Silver Linings Playbook'. The young actress thanked director David O Russell and co-star Bradley Cooper for helping her in her performance.
The film also stars Indian actor Anupam Kher as Dr Cliff Patel. Kher was nominated along with the star cast of 'Sliver Linings Playbook' in the best film ensemble but the award went to 'Argo'. Other nominees were 'Les Miserables', 'Lincoln' and India-shot drama 'The Best Exotic Marigold Hotel'.
Day-Lewis, who has won SAG trophies for his previous movies 'There Will Be Blood' and 'Gangs of New York', was named the outstanding film actor for his memorable turn as the 16th US President Abraham Lincoln. The Steven Spielberg directed movie is leading this year's Oscars with 12 nods.
The British actor had initially rejected the role thinking an American actor should play Lincoln. He thanked his director and Leonardo DiCaprio, who convinced him to reconsider his decision.
The political drama won another trophy with Tommy Lee Jones winning the award for best actor in a supporting role for his performance as Congressman Thaddeus Stevens.
Anne Hathaway continued her winning streak by getting named as the best supporting actress for her turn as fallen woman Fantine in musical 'Les Miserables'.
Accepting her first SAG Award, Hathaway said, "I'm just so thrilled I have dental."
Hathaway has already won a Golden Globe trophy besides winning a nomination at the Oscars in the supporting category.