The pair were joined by the stars of the highly anticipated film, including Tom Cruise who walked Kate up the stairs to pose for photos.
Along with Cruise, they chatted to Jennifer Connelly and Miles Teller.
This wasn't actually the first time Kate and William have reportedly watched the movie.
According to reports, William and Kate went to a special screening of the sequel via an invitation from Cruise himself.
Cruise was aware that William was a big fan of the original movie, which was released in 1986.
"We have a lot in common," Cruise said of William, per My London. "We both love England and we're both aviators, we both love flying."
For more glamorous red carpet looks from this year's Cannes Film Festival, check out our gallery here.