Gwendoline Christie, who currently stars in Game of Thrones as warrior Brienne of Tarth, has also been cast in the production.
The news was announced on the Star Wars website, although it did not say what roles the actresses would play.
Star Wars: Episode VII is due in cinemas on December 18 2015.
“I could not be more excited about Lupita and Gwendoline joining the cast of Episode VII,” Lucasfilm president and producer Kathleen Kennedy said.
“It’s thrilling to see this extraordinarily talented ensemble taking shape.”
Lupita Nyong’o and Gwendoline Christie join the already announced cast of John Boyega, Daisy Ridley, Adam Driver, Oscar Isaac, Andy Serkis, Domhnall Gleeson, and Max von Sydow.
They will join original stars Harrison Ford, Carrie Fisher, Mark Hamill, Anthony Daniels, Peter Mayhew, and Kenny Baker in the new film.
Meanwhile, gossip website TMZ has posted a series of leaked pictures from the set of Episode VII, which began filming in Abu Dhabi last month.
The pictures appear to show a Tatooine-like marketplace and a new alien creature.
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