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.