Boyega -- who plays Finn in the Star Wars series -- confirmed reports that Mad Max: Fury Road star Tom Hardy and English singer Gary Barlow were also "wrapped in Stormtroopers costumes" during filming.
According to THR, the scene in question saw the princes, Hardy and Barlow all standing guard around Boyega's character.
The actor said during the roundtable discussion that the four celebs all decked out in the iconic armor made for a "strange contrast of a weird family."
"It was a great experience," Boyega marveled at the "fun" opportunity to perform alongside members of one of the most powerful and influential families in the world.
Rumors of William and Harry's involvement on the film sprang up in April, when the brothers took a tour of Pinewood Studios in London, where parts of The Last Jedi were filmed. While there, the pair visited the production workshops and met the cast and crew of the latest installment in the blockbuster sci-fi franchise.
Boyega, Mark Hamill, Daisy Ridley and director Rian Johnson were on hand -- along with Chewbacca, BB-8, and producers Ram Bergman and Kathleen Kennedy -- to meet with the duo, and give them a tour of the set.
The star-studded cameos in The Last Jedi are similar to the largely unnoticed cameo Daniel Craig had in The Force Awakens, where he played a Stormtrooper who gets unwittingly manipulated by some Jedi mind tricks.