The Oscar goes to Ang Lee, Argo, Daniel Day Lewis, Jennifer Lawrence
From the White House, First Lady Michelle Obama joined Jack Nicholson to help present the final prize.
''There are eight great films that have every right, as much a right to be up here as we do,'' Affleck said of the other best-picture nominees.
In share-the-wealth mode, Oscar voters spread Sunday's honours among a range of films, with 'Argo' winning three trophies but 'Life of Pi' leading with four.
British actor Daniel Day-Lewis became the first person to win three best actor awards, taking the trophy for his monumental performance as Abraham Lincoln in the Civil War saga 'Lincoln'.
'Hunger Games' star Jennifer Lawrence triumphed in Hollywood's big games, winning the best actress as a damaged soul in 'Silver Linings Playbook', while Taiwanese director Ang Lee pulled off a huge upset as best director for 'Life of Pi'.
Anne went from propping up leaden sidekick James Franco as a presenter at last year's Academy Awards to hefting a golden statue of her own with a supporting-actress Oscar win as a doomed mother-turned-prostitute in the musical 'Les Miserables'.
Austrian actor Christoph Waltz won his second supporting-actor Oscar for a Tarantino film, this time