The group arrived at the ISS on Saturday morning after a successful SpaceX launch from the Kennedy Space Center in Florida on Thursday.
During their time on the orbiting laboratory, the crew will conduct more than 30 scientific experiments and demonstrations focused on human physiology and technological industrial advancements.
Ax-3 is flying a SpaceX Crew Dragon spacecraft named Freedom.
The capsule has flown in space twice previously and gone to the International Space Station each time.
On its flight to the ISS, Dragon executes a series of burns that position the vehicle progressively closer to the station before it performs final docking manoeuvres.