Cate Blanchett wins best actress for her work in <i>Blue Jasmine</i> at the 86th Academy Awards.

Cate Blanchett wins best actress for her work in Blue Jasmine at the 86th Academy Awards. Photo: Reuters

Cate Blanchett has triumphed at the Academy Awards for the second time, winning best actress for her striking performance in Blue Jasmine.

A golden awards season run culminated in an Oscar for playing a New York socialite whose life is disintegrating in Woody Allen's film.

Having collected best supporting actress The Aviator in 2005, she became the first Australian to claim two acting Oscars.

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Blanchett took a deep breath then looked tearful as she headed for the stage to accept the award.

"Sit down you're too old to be standing," she said to an enthusiastic audience. "As random and as subjective as this award is, it means a great deal in a year, yet again, of extraordinary performances by women."

She thanked Allen for writing the screenplay and casting her in the film and insisted that audiences wanted to see films with women at their centre.

"I'm so very proud that Blue Jasmine stayed in cinemas as long as it did," she said. "Thank you so much Woody for casting me. I truly appreciate it."

Blanchett also thanked everyone at the Sydney Theatre company, which she described as one of the world's great theatre companies.

"There is so much talent in Australia," she said.

The role was a triumphant return to the screen after Blanchett's time co-directing the STC with husband Andrew Upton.

Allen has said he wrote the part of a fragile wife of a wealthy businessman for her.

Despite the revival of longstanding sexual abuse allegations against Allen, Blanchett beat three former Oscar winners – Sandra Bullock (Gravity), Judi Dench (Philomena) and Meryl Streep (August: Osage County) – as well as five-time nominee Amy Adams (American Hustle).

Her awards season run included wins at the Golden Globes, Screen Actors Guild and British Academy awards.

"Inwardly she's falling apart at the seams," Blanchett said of her character on the red carpet. "That was a fascinating and quite tragic thing to play."

Her stellar international career over the past 15 years has also delivered Oscar nominations for Elizabeth, Notes On A Scandal, I'm Not There and Elizabeth: The Golden Age.

Blanchett is about to shoot Todd Haynes' Carol, a romantic drama about a department store staffer who falls for an older married woman. Based on a Patricia Highsmith novel, it co-stars Rooney Mara.