"Lift off Polaris Dawn!" the company wrote on social media site X.
This is Isaacman's second spaceflight. This time, he had to split the cost with SpaceX and helped finance brand new spacesuits.
Pushing boundaries
The mission is planning to venture further than any manned spaceflight has since NASA's Apollo flights.
Spacewalks are considered one of the most dangerous things an astronaut can do in the harsh vacuum of space.
The walk outside the capsule is scheduled to take place late on Wednesday or early Thursday, by which point the ship should be far beyond the International Space Station (ISS) at an altitude of 870 miles (1,400 km).
Later on Tuesday, SpaceX confirmed that Polaris Dawn was in orbit.
The mission had been delayed several times due to technical issues and inclement weather. Because the Dragon crew capsule will not dock with the ISS, conditions had to be perfect for the launch.
