The actress, who stars in the movie as Carol Danvers a.k.a. the eponymous Captain Marvel, shocked audiences as she showed up at cinemas across the U.S..
Wearing a custom tracksuit in the style of the iconic uniform that she wore in the film, Larson appeared before the crowd to thank them for their support.
She was also seen carrying a soft drink with her own face on it as she casually entered the auditorium.
The official Marvel Twitter account shared photos and videos from the AMC Clifton Commons 16 movie theatre in Clifton, New Jersey, on Saturday night, March 09.
"I just heard that I was on the cups and popcorn and I wanted to see for myself," Larson said to the New Jersey moviegoers in a video posted to the site. "Thank you so much for coming. You guys are so awesome to come opening weekend."
Throughout the evening, Larson also worked the concessions stand, serving popcorn and soda to fans.
The film, which is Marvel Studios' first female-led feature, wrapped up the weekend with $153 million (£117.5 million) at the North American domestic box office.
The movie also topped the global box office, opening with $302 million (£232 million) on its first weekend.
Comscore's senior media analyst Paul Dergarabedian remarked on "Captain Marvel"'s success, praising the "Avengers: Endgame" actress' historic performance as "just what blockbuster starved audiences have been waiting for."