The Academy Award winner tweeted before-and-after images, saying the magazine "edited out and smoothed" her hair. She added the hashtag "dtmh (don't touch my hair)."
On Instagram, the Kenya-raised star of "12 Years a Slave" and "Star Wars: The Last Jedi" said "there is still a very long way to go to combat the unconscious prejudice against black women's complexion, hair style and texture."
The magazine said Friday that it "apologized unreservedly to Lupita Nyong'o." It said it had not altered the images itself or asked the photographer to do so, and "is committed to representing diversity throughout its pages."
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.