The Oscar winner looked absolutely stunning on the red carpet outside the El Capitan Theatre in Hollywood, wearing a custom J. Crew lime green top and a shimmering, swinging, multi-slit metallic skirt.
The 33-year-old star later covered up against the crisp evening air in a denim jacket, and posed with her 12-year-old co-star, Neel Sethi.
Nyong'o spoke with ET's Cameron Mathison at the premiere where she opened up about her connection to the beloved original animated Jungle Book from 1967, and even sang some of the film's iconic tune, "The Bare Necessities."
"Jungle Book was definitely a part of my childhood," Nyong'o shared. "I loved Mowgli and the freedom with which he seemed to live his life. He'd swing from vine to vine and he had all these cool animal friends and he went on an adventure to find out where he belonged. And I just really identified with that and wished that I could experience such freedom."
In Disney's new retelling of the iconic stories of Rudyard Kipling, Nyong'o plays Raksha, an Indian wolf who raises Mowgli [Sethi], an orphan human baby, as her own cub.
"I just absolutely love that world," Nyong'o told ET, "and a part of me thought that I ought to live there."
Disney's live-action reimagining of The Jungle Book hits theaters April 15.