She said she “never dreamed” she would be praised for her looks and find herself on the US weekly’s cover.
Nyong’o shot to fame in the film 12 Years a Slave, winning the Oscar for best supporting actress last month.
She subsequently won her first major endorsement when she became the new face of French cosmetics giant Lancome.
Nyong’o said it was “exciting and a major, major compliment” to be on the cover of People.
“I was happy for all the girls who would see me on it and feel a little more seen,” she is quoted by the magazine as saying.
She received an Academy Award this year in the category of Best Supporting Actress for her portrayal of Patsey in the Steve McQueen-directed film.
The Mexican-born Kenyan beauty was joined by a cast of Hollywood A-listers who have headed the list, including Julia Roberts, Cindy Crawford, Tom Cruise and Beyonce. This year she topped others on the list including “The Americans” star Keri Russell, singer Pink and Johnny Depp’s future wife, actress Amber Heard.
During the 2014 awards season Nyong’o was often hailed for being one of the most fashionable on the red carpet. She made headlines in February for a moving speech she gave while accepting the best breakthrough performance award at the 7th annual Black Women in Hollywood luncheon.
“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.”
The actress told “Today’s” Savannah Guthrie that she was moved by People naming her the most beautiful.
“I’m flattered, but flattered sounds like such a flighty word, you know? I’m flattered with, like, gravitas under it,” she said.