Joss Whedon's superhero ensemble won by a landslide vote in an online survey conducted by The Los Angeles Times.
It scored 85% of the votes, easily beating nearest contender Prometheus which scored less than 5%.
Other contenders included Seth MacFarlane's black comedy Ted, Pixar's Brave and Paul Thomas Anderson's The Master.
Last year's poll winner was The Twilight Saga: Breaking Dawn - Part 1.
The Dark Knight Rises cinematographer Wally Pfister sparked controversy last year after he dubbed The Avengers "an appalling movie".
Whedon himself has been modest about the film's success, commenting last year: "I don't think it's a perfect movie. I don't even think it's a great movie."
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Gallery - The Avengers in pictures: