The actor said she became an instantly huge fan of Peele thanks to Get Out, which came out while she was filming Black Panther. In fact, she saw it five times.
"Black Panther was intense and time-consuming and all-encompassing," Nyong'o said. "But I found time to go to the cinema five times in one month while I was working on that film to watch Get Out."
Nyong'o said she would talk about the movie in phone calls with her brother and best friend, parsing over all the details and callbacks and new things they noticed by rewatching it.
"He created a cinematic experience that we could grab and take with us," she said. "It became such a joy to just live in his mind."
"I was just like, I need to work with that guy right there," she said.
So, when Nyong'o got the offer for Us, there was no question she was in.
"Of course I'm doing it! Whatever it is," she said. "Now, let me read the script."
Nyong'o said she stopped watching horror movies as a child "when I realized I didn't have to prove anything." She said she was really scared while reading the script.
"I read the script kind of with one eye, being like 'oh god, oh god, oh god,' and my shoulders are going up up up up up," she said. "And I finished, and was like, this is amazing. Also, what is it about? Like, what else is it about? Because I could tell it was more than met the eye."
The actor said she pretty much only talked to Peele as a "formality" and knew she was going to say yes.
"He was like, 'And if you do this film, and if...' and I was just laughing," she said, "Because of course I'm going to do this film!"
Despite the fact that she "played it cool," as Peele said, Nyong'o said she really wanted to make sure first that she "had something to offer" in playing the role.
"He's so smart, and I could tell that this was more than just the surface," she said. "And I wanted to really make sure I had an instinct for the thing he wanted to say."
Watch the full interview below.