While speaking at Facebook's London office to mark International Women's Day on Sunday, the 24-year-old and the United Nations Ambassador for Women said the concerned website targeted her after she spoke up for women's rights.
"After I gave my speech (at the United Nations) there was a website threatening to release naked pictures of me.
"I knew it was a hoax, I knew the pictures didn't exist, but I think a lot of people that were close to me knew gender equality was an issue but didn't think it was that urgent, that it was a thing of the past.
"And then when they saw that the minute I stood up talking about women's rights I was immediately threatened, I think they were really shocked, my brother was particularly upset.
"This is a real thing that's happening now, women are receiving threats. I was raging, it made me so angry, I was like, this is why I have to be doing this. If anything, if they were trying to put me off it, it did the opposite."
In September 2014, a webpage entitled Emma You Are Next, featuring an image of the star next to a countdown clock, appeared to have been created by a user of image-sharing website 4chan, on which lewd photographs of celebrities including Jennifer Lawrence and Kate Upton were posted.