Nyong'o is tapped to play Rakcha, a mother wolf who adopts lead character Mowgli, while Johansson is in talks for the role of Kaa, a python who hypnotizes her prey. Idris Elba will voice the villainous tiger Shere Khan.
The Disney film, a mix of live action and CGI, will be directed by Jon Faveau, according to The Hollywood Reporter.
Warner Bros. also has a "Jungle Book" film in development starring Andy Serkis.
Nyong'o, 31, was raised in Kenya. The Hollywood newcomer won a Best Supporting Actress Oscar for her role in 2013's "12 Years A Slave."