The post, captioned, "more than a facial," could be a Throwback Thursday snap from the set of Star Wars: The Last Jedi, which wrapped filming last year, or a peak at Nyong'o's character in Marvel's Black Panther.
Production on Black Panther began in Atlanta in late January and will also shoot in South Korea, according to a Marvel news release.
Chadwick Boseman reprises his role as T'Challa (aka Black Panther) in the Ryan Coogler-directed film, which also stars Michael B. Jordan, Sterling K. Brown, and The Walking Dead's Danai Gurira.
Nyong'o plays, Nakia, T'Challa's love interest and member of the team of all-female bodyguards in the fictional African nation of Wakanda.
Much like Black Panther, details surrounding the upcoming Star Wars film are being kept under wraps.
Luckily, Nyong'o doesn't mind keeping a secret.
"I love shutting up. I love it. I love the fact that I don't have to talk about Star Wars," she told Cinema Blend in an interview published on Wednesday. "I feel like I have a secret that everybody else wants to know about. That's powerful. I love it. I feel a little sad every time more information is revealed."