Day-Lewis won the second best actor Oscar of his career, picking up the coveted award for his portrayal of a ruthless oil prospector in There Will Be Blood.
The actor, whose first Oscar came for his performance in the 1989 film My Left Foot, had been the overwhelming favourite to claim the Oscar after sweeping top honours at several award shows this year.
Day-Lewis knelt as he received his award from actress Helen Mirren, last year’s winner for her role in The Queen quipping: “That’s the closest I’ll ever come to getting a knighthood.”
“My deepest thanks to the members of the academy for whacking me with the handsomest bludgeon in town,” he added.
The 50-year-old star, who is renowned for the selectiveness and intense research with which he approaches each of his roles, has been nominated for an Oscar on two other occasions.
In There Will Be Blood, Day-Lewis plays a scheming entrepreneur who sets out to build a fortune in the early days of the oil industry in turn of the century California.
Glen Hansard picked up the Achievement in Music (Original Song) Award for Falling Slowly with co-star Marketa Irglova for the movie Once.
Hansard said: “I kind of feel a bit like a plumber at a flower show over here. I kind of feel like we’re totally outside of all this but at the same time I’m kind of just trying to accept that it all happened. It’s been an incredible ride, this whole thing.”
But it was two of the most imaginatively twisted minds in modern film, Joel and Ethan Coen, who completed their journey from the fringes to Hollywood’s mainstream as their crime saga No Country for Old Men won a leading four Academy Awards, including best picture.
In a year when the quirky, offbeat and just plain weird storytelling of the Coens triumphed at the biggest ceremony in show business, the oddball brothers found a lot to like in their fellow nominees.
“It sounds like a cliche, but all the movies that were nominated were really interesting to me personally, and that isn’t always the case,” Joel Coen said.
“All of them to me personally I thought were fantastically good movies.”
The Coens’ brooding, bloody tale of violence in a desolate corner of west Texas was the American standard-bearer for an Oscar show that otherwise had an international flair.
All four acting prizes went to Europeans: Frenchwoman Marion Cotillard, the best-actress winner for La Vie En Rose; Spaniard Javier Bardem, who took supporting actor for No Country for Old Men; and Briton Tilda Swinton for supporting actress for Michael Clayton.
The globe-trotting thriller The Bourne Ultimatum swept all three of its categories, film editing, sound editing and sound mixing. Other winners included three films set around Britain and Europe: Atonement (music score), Elizabeth: The Golden Age (costume design) and Sweeney Todd: The Demon Barber of Fleet Street (art direction).
Host Jon Stewart started his opening monologue with a wisecrack about the 100-day writers’ strike that ended just in time for the Oscars to come off as usual.
“These past three and a half months have been very tough. The town was torn apart by a bitter writers’ strike, but I’m happy to say that the fight is over,” Stewart said.
“So tonight, welcome to the makeup sex.”
Elsewhere at the ceremony, exotic dancer-turned-scriptwriter Diablo Cody took best original screenplay for the quirky, verbose comedy Juno — her first movie.
“I’m shocked by the popularity of the film,” she said.
“I mean, when you write basically an independent movie about, you know, a pregnant teenager and you make it for $7m (€4.7m) you never, ever think it’s going to become this phenomenon.”
Box office hit Ratatouille claimed the Oscar for Best Animated Feature Film while the Austrian Holocaust-era drama The Counterfeiters picked up the Oscar for Best Foreign Language Film, the first win for Austria in the category.