The British entrepreneur will be on his space tourism company’s 11 July flight, after bringing forward his participation.
Mr Branson had not been due to ride on VSS Unity for test flights, but Virgin Galactic confirmed his participation has been expedited.
This had been the subject of intense speculation since Mr Bezos announced he would be onboard his company Blue Origin’s flight on 20 July.
Mr Branson will now be “testing the private astronaut experience” alongside four mission specialists and two pilots.
“I’ve always been a dreamer. My mum taught me to never give up and to reach for the stars. On 11 July, it’s time to turn that dream into a reality aboard the next @VirginGalactic spaceflight,” tweeted Mr Branson.
It will be Virgin Galactic’s fourth crewed test flight using VSS Unity, a spaceplane that is dropped from a carrier in mid-air before shooting up to the very edge of space.
Those onboard will experience two minutes of weightlessness before returning to the company’s New Mexico launch headquarters.
The flight will be “the first to carry a full crew of two pilots and four mission specialists in the cabin, including the company’s founder, Sir Richard Branson, who will be testing the private astronaut experience,” Virgin Galactic said in a statement.
Mr Bezos will fly onboard Blue Origin’s New Shepard suborbital rocket along with legendary aviator Wally Funk, her brother and an unnamed passenger who bid $28m in an auction.
Ms Funk, 82, was a member of the Mercury 13 Women in Space Program, but after completing her training it was cancelled and she never went into space.
She also holds a ticket to travel on a Virgin Galactic flight.
In May the company’s third test flight reached a height of 89.2km, or 293,000ft.
US officials consider anyone who has flown above 80km to be an astronaut, while outer space starts at the Karman Line, 100km above the Earth’s surface.
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