The actress - who won the 'Best Supporting Actress' Oscar for Michael Clayton in 2008 - told The AP that she wasn't upset at all that the Academy chose not to recognise her performance as one of the year's best.
"I wasn't disappointed. I didn't know for hours, but someone was telling me apparently everyone else was disappointed," Swinton explained. "I had very low expectations, so perhaps my expectations were a bit lower than everybody else.
"I am a good gambler, so I knew we were not really going to be in there. I am amazed that our little film got as far as it did."
Swinton's portrayal of a woman losing her grip on reality in We Need to Talk About Kevin has received Globe Globe, BAFTA and Screen Actors Guild nominations.
The star has already won the European Film Award for 'Best Actress' and the National Board of Review of Motion Pictures Award for 'Best (Lead) Actress'.
This year's Academy Award nominees for 'Best Actress' are Albert Nobbs star Glenn Close, Viola Davis for The Help, The Girl with the Dragon Tattoo's Rooney Mara, Meryl Streep for The Iron Lady and Michelle Williams for her portrayal of Marilyn Monroe in My Week with Marilyn.
The 84th Academy Awards airs on February 26, 2012 on ABC.
> Oscars 2012: Academy Awards nominations - in full
> Jamie Bell, Tilda Swinton for Snow Piercer?
Watch a trailer for We Need to Talk About Kevin below: