Japan's Daisuke Enomoto had been due to blast off for the International Space Station on September 14, but the Main Medical Commission decided that he was medically unfit to fly to space.
Tehran-born Anousheh Ansari, who turns 40 next year, will become the first female space tourist.
"The decision has been made by the Board of Chief Designers. It will be formalized next week," Igor Panarin said.
Three other tourists have flown to the ISS for a reported $20 million each. The first was U.S. businessman Dennis Tito, who was followed by South African Mark Shuttleworth and American Greg Olsen.