The seemingly odd pairing is detailed in a new profile in Vanity Fair ... which claims Johnny is getting the royal treatment over in Saudi Arabia.

MBS hosted JD in the Saudi Kingdom for nearly 2 months last year, putting Johnny up in royal palaces and transporting him in helicopters, yachts and a private plane ... according to Vanity Fair.

Unsurprisingly, it sounds like money is a huge factor in this "bromance" ... Johnny's shooting movies in Saudi Arabia as he waits on a potential 7-figure deal to make him one of the nation's global cultural ambassadors.

MBS and the Saudis have been trying to buy their way into all sorts of global industries as part of MBS' grand plan to make people overlook his country's reported human rights abuses ... and the Crown Prince has been investing big in movies.

Johnny and MBS are said to have begun their friendship in July 2022 when Depp was shooting "Jeanne du Barry," a film bankrolled by the Saudis.

They've grown closer ever since, to the point where Johnny says he felt comfortable enough to ask MBS about the killing of Washington Post journalist Jamal Khashoggi.

The VF profile says MBS told Depp he didn't order Khashoggi's dismemberment, but took responsibility ... claiming he just wanted the reporter arrested because Khashoggi had become a rogue operative working to undermine the country.

Johnny definitely seems to be buying what MBS is selling in terms of a cultural revolution in Saudia Arabia.

Depp tells VF ... "Though I admit I was somewhat naïve at first to what was transpiring in the region, I’ve since experienced firsthand the cultural revolution that is happening there."

JD added, "I've had the opportunity to meet people from various parts of the region who have been most welcoming in sharing with me their culture, their traditions, and their stories."

Saudia Arabia is also financing Depp's next crack at directing a movie ... a biopic about Italian artist Amedeo Modigliani starring Al Pacino.