The award was announced by Reese Witherspoon, who won a Best Actress Oscar in 2006 for "Walk the Line."
Bale gave a shout-out to the man he played in the film, Dicky Eklund, and thanked his wife and young daughter, "who has taught me so much more than I'll ever be able to teach her."
The English-born actor, who also plays Batman in the current film revival of the comic-book franchise, is known for his intense performances (and occasional rant). He also won a best Supporting Actor award at the Golden Globes in January.
Earlier in the ceremony, "The Fighter" also won a Best Supporting Actress Oscar for Melissa Leo.
Bale beat Geoffrey Rush ("The King's Speech"), Mark Ruffalo ("The Kids Are All Right"), John Hawkes ("Winter's Bone") and Jeremy Renner ("The Town").