The 50-year-old actress thought it was ''ridiculous'' when she learned she had scooped the 2015 honour and didn't tell anyone.
Sandra said: ''I just said, 'That's ridiculous'. I've told no one.''
The Oscar-winning actress insisted that she thinks beauty comes from within, tending to prefer ''the ones who aren't trying''.
Speaking to PEOPLE magazine, Sandra said: ''Real beauty is quiet. Especially in this town, it's just so hard not to say, 'Oh, I need to look like that'.No, be a good person, be a good mum, do a good job with the lunch, let someone cut in front of you who looks like they're in a bigger hurry. The people I find most beautiful are the ones who aren't trying.''
The 'Miss Congeniality' star also confessed that the best compliments she gets are from her five-year-old son Louis, who told her she's ''not old'' but ''just happy'' and made her realise that beauty isn't just about looks.
Sandra said: ''I was putting (Louis) to bed and told him that even when I'm old and grey and more wrinkly than I am now, I'll still love him and want to tuck him in. And he asked why I have wrinkles, and I said, 'Well, I hope some of them are from laughing so much.' And he touched my face and said, 'You're not old, you're just happy.' ''
Also featured in the publication's Most Beautiful issue are stars including Laverne Cox, Jenna Dewan-Tatum, Taraji P. Henson, Ariana Grande and Gabrielle Union.
Previous winners of the accolade include Jennifer Aniston, Julia Roberts, Beyonce and Lupita Nyong'o.
Subject: Sandra Bullock has been named the World's Most Beautiful Woman 
