ISS deputy director Robyn Gatens said there would be two short private astronaut missions per year.
NASA said that tourists would be allowed to stay for up to 30 days at the ISS with the trip made via a US spacecraft.
“Nasa is opening the International Space Station to commercial opportunities and marketing these opportunities as we’ve never done before,” chief financial officer Jeff DeWit said in New York.
It will be down to private commercial firms to organise crews and ensure that the tourists meet the medical and training requirements needed to be an astronaut.
It is a new approach from NASA who have previously banned any commercial use of the space station.
Astronauts also have been forbidden from being involved in profit-making research.
The space agency recently announced that it planned to return to the moon by 2024, taking the first woman there and the first person in decades.
The first component of the ISS was launched into orbit in 1998, and the station has been continually occupied since November 2000.