The royals, accompanied by 500 children and adults from charities they support, had a wand lesson, visited the Great Hall of Hogwarts School and saw props, costumes and models from the Potter series in the company of the boy wizard's creator, author J.K. Rowling.
William also seemed taken with props from "The Dark Knight" Batman trilogy. "I'm a very happy man," he joked after exploring the Batmobile and sitting astride the Batpod motorcycle.
Kate, who is six months pregnant and wore a polka-dot dress, smiled indulgently at her husband.
In a speech to Warner Bros. executives, William, 30, said he was "over the moon just to have seen the real Batmobile and Batpod."
"On the other hand Harry's just excited to see a real life talking owl in the Harry Potter studios," William said of his 28-year-old brother. "I haven't told him yet that Harry Potter is fictional, so please keep the secret for a little longer."
Friday was the official opening of Warner Bros.' Studios Leavesden, a former World War II airdrome 20 miles northwest of London. Warner Bros. has spent $155 million redeveloping the facility, where the eight Potter films were shot, into Europe's largest filmmaking complex.