The Oscar-winning actress took to social media to accuse the fashion magazine of digitally altering the look of her hair in a cover shot to make it "fit a more Eurocentric notion of what beautiful hair looks like."
She posted before and after pictures
on Instagram and Twitter to show how her hair had been changed, along with a statement criticizing the magazine.
"I am disappointed that @graziauk invited me to be on their cover and then edited out and smoothed my hair," she wrote. "Had I been consulted, I would have explained that I cannot support or condone the omission of what is my native heritage with the intention that they appreciate that there is still a very long way to go to combat the unconscious prejudice against black women's complexion, hair style and texture."
Nyong'o explained she had grown up thinking "light skin and straight" hair were the standards of beauty, but she now sees the beauty in her "dark skin and kinky, coily hair."
"Being featured on the cover of a magazine fulfills me as it is an opportunity to show other dark, kinky-haired people, and particularly our children, that they are beautiful just the way they are," she wrote.
But her high hopes for the cover photo were crushed.
Grazia UK apologized to Nyong'o via a statement on social media
but said that "at no point did (it) make any editorial request to the photographer for Lupita Nyong'o's hair to be altered on this week's cover, nor did we alter it ourselves."
But the magazine did say it should have ensured it was aware of all alterations made to the photo.
Lupita won the Academy Award for best supporting actress for her portrayal of the slave Patsey in "12 Years a Slave" (2013). She co-stars next year in the Marvel movie "Black Panther."