Jeff Bezos will attempt to fly to space on board a rocket built by Blue Origin, the space company he founded, as part of its first human flight in July.
The Amazon founder’s brother, Mark Bezos, will also be on board for the trip, as well as a third passenger to be decided by an ongoing auction.
“Ever since I was five years old, I’ve dreamed of travelling to space,” the 57-year-old billionaire said in an Instagram post.
“To see the Earth from space, it changes you. It changes your relationship with this planet, with humanity,” he said. "It's an adventure – it's a big deal for me."
The first human flight of Blue Origin's New Shepard spacecraft is planned for July 20.
Bidding is under way for the final seat on the rocket, with the highest bid currently at $2.8 million, according to the company’s website.
The process will last until June 10 and conclude in a final phase on June 12, with a live online auction.
Named after Nasa astronaut Alan Shepard, who in 1961 became the first American to go to space, the New Shepard rocket is a reusable rocket designed to take a small crew of passengers on a short trip over the Karman Line, which marks the boundary between the Earth's atmosphere and outer space.
Space enthusiasts had speculated over whether the Blue Origin founder would be a passenger on the first crewed New Shepard mission. The 11-minute flight is seen as a landmark moment for commercial space travel.
Mr Bezos has sparred with the billionaire tech investor Elon Musk in recent months over their respective space projects, with each pouring considerable amounts of their fortunes into their space companies.
Though Mr Musk's SpaceX is better known after a string of publicity stunts as well as ground-breaking successes, such as the recent successful test flight of its Starship prototype, Mr Bezos's Blue Origin has been around for longer.
Founded in secret in 2000, the existence of Blue Origin only became public in 2003 when Mr Bezos began purchasing the land that now forms the company’s testing facility in West Texas.
The company's activities and long-term goals have been mostly shrouded in secrecy, in stark contrast to its rivals.
The Amazon founder has piled more and more of his vast wealth into the project in recent years, and has been spending an estimated $1 billion on it each year since 2016.
It may be small change for the world’s richest man, but his attachment to the project is clear.
He is said to sign off emails with the company’s motto, "Gradatim Ferociter", Latin for "step by step, ferociously", which also appears on his coat of arms.