ABC News' Suzan Clarke reports:

Lupita Nyong'o has taken Hollywood by storm, but the Kenyan beauty revealed that she experienced "self-hate" because of her dark complexion and used to pray for lighter skin.

The 31-year-old who won an Academy Award for best supporting actress for her role as the slave Patsey in the acclaimed film "12 Years a Slave," made the revelation on February 27 while giving a speech at Essence Magazine's annual Black Women in Hollywood luncheon.

In a moving speech, Nyong'o she said used to be teased and taunted for her "night-shaded" skin, and felt "unbeautiful."

Addressing the people at the event, Nyong'o said she wanted to share her past pain because of a letter she received from a young fan.

Nyong'o read from the letter: "Dear Lupita," she read, "I think you're really lucky to be this black but yet this successful in Hollywood overnight. I was just about to buy Dencia's Whitenicious cream to lighten my skin when you appeared on the world map and saved me."

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"My heart bled a little when I read those words," Nyong'o told the gathering. "I could never have guessed that my first job out of school would be so powerful in and of itself and that it would propel me to be such an image of hope in the same way that the women of 'The Color Purple' were to me."

"The Color Purple" is a 1985 film from director Steven Spielberg that is based on Alice Walker's Pulitzer Prize-winning book of the same name. It tells the story of a young African American woman who faced racism, sexism and poverty in the 1900s.

Through tears, Nyong'o revealed that her own inner turmoil as a girl and teenager had mirrored that of her letter-writing fan.

"I remember a time when I too felt unbeautiful," she said. "I put on the TV and only saw pale skin, I got teased and taunted about my night-shaded skin and my one prayer to God the miracle worker is that I would wake up light skinned … I tried to negotiate with God, I told him I would stop stealing sugar cubes at night if he gave me what I wanted."

God was "unimpressed" with her pleas, she said, and her "self-hate" grew worse when she became a teenager, even though her mother would tell her that she was beautiful.

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It was only when African supermodel Alek Wek came on the scene that Nyong'o said her outlook began to change.

"A celebrated model, she was dark as night, she was on all of the runways and in every magazine and everyone was talking about how beautiful she was. Even Oprah (Winfrey) called her beautiful and that made it a fact … My complexion had always been an obstacle to overcome and all of a sudden, Oprah was telling me it wasn't. It was perplexing and I wanted to reject it because I had begun to enjoy the seduction of inadequacy. But a flower couldn't help but bloom inside of me," she said.

Even then, she believed that, all around her, the preference for lighter skin prevailed.

"To the beholders that I thought mattered, I was still unbeautiful. And my mother again would say to me, 'You can't eat beauty. It doesn't feed you.' And these words plagued and bothered me; I didn't really understand them until finally I realized that beauty was not a thing that I could acquire or consume, it was something that I just had to be," she said.

She finally realized, she said, that there was "no shade" to inner beauty.

The members of the audience - including actresses Regina King, Angela Bassett and Winfrey - paid rapt attention to Nyong'o's words.

"There were tears," recalled Dawnie Walton, the deputy managing editor of Essence. "People were definitely spellbound."

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Video of Nyongo's speech has gone viral. Posted to YouTube March 1, the speech had been viewed nearly 2 million times as of Wednesday night. Commenters praised her honesty, commended her poise and thanked her for being an inspiration.

Dawnie Walton, the deputy managing editor of Essence magazine, explained why Nyong'o's words were having such impact.

"I think so many black women find special joy in her success because she is someone that doesn't look like the average actress in Hollywood and she has been embraced," Walton said.