An onslaught of questions about the passenger's identity on Twitter has failed to coax any details from Musk, except one hint.
"He's paying a lot of money that would help with the ship and its booster", Musk said on Monday.
SpaceX COO Gwynne Shotwell gave a more generous time frame for BFR's debut during a TED Talk in April, saying it would launch "within a decade".
Musk, a master showman, is adept at inspiring a massive audience of followers for his pursuit of electric cars and other clean-energy endeavours critical to combating global warming.
It wasn't revealed how much Maezawa paid for the flight, but Musk did announce that the businessman approached him about the flight. A former drummer in a rock band, he built shopping website Zozotown, a popular destination for younger consumers, from a mail-order music album business.
As curiosity mounts over the futuristic BFR, Musk tweeted 3 images, showing it will consist of a first stage with engines and fuel systems, and a second stage with the spacecraft where the passengers will ride.
'They will be asked to create something after they return to Earth. He said about BFR, it's "making people excited about the future - about getting up in the morning". "Please don't say no". And you certainly can't decide basically on what he says. "And it sounds insane but everything we've ever done has sounded insane to people, both people that love us and people that don't like us so much".
Can Elon Musk and SpaceX pull this off? The company's Space Dragon crew capsule, which is meant to take astronauts to the International Space Station, missed an initial target date of 2017 and won't see a manned test until 2019.
The BFR was first announced in 2016, touted as the most powerful rocket in history, even more potent than the Saturn V Moon rocket that launched the Apollo missions five decades ago. You have to be pretty loaded to score a tourist spot on a spaceship. The craft created to ferry humans safely to and from the orbiting lab will take off from Florida's Kennedy Space Center in 2019.
NASA is planning its own lunar flyby with a crew around 2023.
However, Musk used social media to drop hints ahead of the announcement.
But did add: "It's not 100 percent certain we can bring this to flight".
SpaceX CEO Elon Musk announced Monday night that entrepreneur Yusaku Maezawa would be the first private person to fly aboard its Big Falcon Rocket (BFR) launch vehicle. He didn't discuss the other person.
Maezawa is an art enthusiast who plans to fly on the trip as early as 2023. "In order to minimize the development risk and cost, we made a decision to "commonize" the engine between the booster and ship", Musk said, adding that Raptor engines that are optimized for vacuum conditions could be added back in later. 'We are honored that he chose us'.