The following morning at 2:31 AM EST (07:31 UTC), Dragon will autonomously undock from the Harmony module and maneuver away from the station.
The rendezvous with the orbiting lab marks the first time that Crew Dragon, created to eventually carry astronauts, has ever flown and raises the stakes for rival Boeing Co, which also has a contract with Nasa as part of what is known as the agency's "Commercial Crew" programme.
It is expected to reach the ISS later on Sunday.
A SpaceX rocket with a newly designed unmanned crew capsule blasted off on Saturday for the International Space Station, in a key milestone for Elon Musk's space company and NASA's long-delayed goal to resume human spaceflight from USA soil later this year.
A Falcon 9 Block 5 rocket lofted Dragon to orbit from LC-39A at NASA's Kennedy Space Center in Florida, kicking off the first orbital test flight of NASA's Commercial Crew program.
While SpaceX has sent plenty of cargo Dragons to the space station, a Crew Dragon is a different beast. The celebration was a milestone for Musk, who launched the company in 2002 with the goal of taking humans into space and one day colonizing Mars.
In order to certify Crew Dragon to carry humans, NASA and SpaceX will complete a series of four test flights, of which Demo-1 is the second.
The launch of the new astronaut capsule on a week-long round trip to ISS is seen as a key step towards resuming manned space flights from U.S. soil after an eight-year break.
Boeing aims to conduct the first test flight of its Starliner capsule in April, with astronauts on board possibly in August.
Boeing is also in the race to end NASA's eight-year drought of launching USA astronauts on US rockets from USA soil. The Starliner is now due to make its first uncrewed test flight no earlier than April, and its first crewed flight no earlier than August.
"We're going to learn a ton from this mission, " said NASA's commercial crew program manager, Kathy Lueders. NASA selected SpaceX and Boeing to design and build crew-carrying spacecraft to shepherd astronauts to and from the space station - replacements for the Space Shuttle, which NASA retired in 2011.
Shortly after liftoff, the Falcon 9's first stage came back to Earth, touching down on SpaceX's drone ship "Of Course I Still Love You" which was ready and waiting off the Florida coast.
California's SpaceX firm has carried out a demonstration of a new rocket and capsule combination.
Crew Dragon holding at 20 meters Crew Dragon holds at 20 meters from the station's forward docking point during its inaugural test flight on 3 March 2019.
The dummy in the capsule - which SpaceX's Hans Koenigsmann prefers to call a "smartie" - is fitted with monitors to test the forces to which future astronauts will be subjected on take-off and when they return to the Earth's atmosphere and then splash down in the Atlantic, slowed down by giant parachutes.