The actress shared the stage with costar Channing Tatum and read from a script about their new sci-fi film, Jupiter Ascending, which opens July 18.
"She becomes quite a badass," Kunis, 30, told festival goers about her character, who is the Queen of the Universe.
Tatum, 33, who welcomed his first daughter, Everly, last May, gallantly escorted her, taking her hand as they both entered the stage on the festival's last day.
Later, Tatum and Kunis, in a dark chiffon dress, stopped by PEOPLE's photo booth, where she was seen whispering into his ear.
After staying for about 20 seconds, they headed over to a hospitality area where Kunis indulged in a snack and Tatum drank wine. The busy duo and their team then left and headed to the airport.
Reporting by MARK GRAY