On Sunday the 55-year-old won the gong for his role in Steven Spielberg's biopic, Lincoln.
Accepting the Academy Award from Meryl Streep, he said: "I really don't know how any of this happened."
The triple win puts Day-Lewis ahead of Dustin Hoffman and Marlon Brando, who are among the actors to pick up statue twice.
Co Armagh man Seamus McGarvey missed out on the Best Cinematography award for Anna Karenina, as Life of Pi's Claudio Miranda went home with the win. Ang Lee was named best director for the fantasy film, which was also named best original score and best visual effects.
Anne Hathaway was named best supporting actress for her portrayal of Fantine in Les Miserables, while Adele performed her Bond theme Skyfall live for the first time ever. She won in the best original song category.
Ben Affleck's Argo won best film, in a category introduced from the White House by first lady Michelle Obama.
It is the second time Affleck has won a gold statue - he won Best Original screenplay in 1997 for Good Will Hunting.
"I never thought I would be back here and I am because of so many of you who are here tonight," he said during his speech.
"It doesn't matter how you get knocked down in life, all that matters is that you get up."
Newcomer Jennifer Lawrence, who was awarded best actress for Silver Linings Playbook, made headlines for another reason, as she stumbled on stage in her Dior gown.
"You guys are just standing up because you feel bad that I fell over and that's embarrassing," she said.
"This is nuts."
Elsewhere Quentin Tarantino's Django Unchained collected two awards - best supporting actor for Christoph Waltz and best original screenplay.
Best animated feature film was awarded to Brave, a cartoon set in the Scottish Highlands and featuring the voices of Billy Connolly, Emma Thompson and Julie Walters.