They are scheduled to spend 12 days on board the ISS and Maezawa has said he plans to document his journey for his YouTube channel with over 700,000 subscribers.
"I want to tell you that dreams do come true," he said in Moscow on Thursday. "Go for goal. Everything depends on you."
He will be the first space tourist to travel to the ISS with Russia's space agency Roscosmos since 2009 when Canadian Guy Laliberte, co-founder of Cirque du Soleil, travelled to the station.
Earlier this month, Roscosmos sent an actress and a director to the ISS where they are filming scenes for the first movie in orbit. They will return to Earth on Sunday.
Maezawa's three-person crew will travel aboard the Soviet-designed Soyuz rocket that for decades has ferried astronauts from around the world to the ISS.
Last year, however, Russia lost its monopoly for ISS flights to Elon Musks's SpaceX that successfully delivered NASA astronauts to the station in a Crew Dragon capsule.
SpaceX made history this year by sending the first all-civilian crew around the Earth's orbit in a mission called Inspiration4.
The US company also plans in 2023 to take an all-civilian mission on a flight around the moon, funded by Maezawa who plans to be among the eight people on board.
Competition in the space tourism sector is heating up as more players emerge.
Blue Origin, the company of Amazon founder Jeff Bezos, completed two missions beyond the Earth's atmosphere this year.
Virgin Galatic of billionaire Richards Branson offers a similar experience of a few minutes in weightlessness before coming back to Earth.
Both Bezos and Branson were aboard for their company's respective maiden voyage.
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© 2021 AFP