NASA astronauts Raja Chari, Tom Marshburn, and Kayla Barron, as well as European Space Agency astronaut Matthias Maurer, will spend six months at the ISS conducting scientific research and monitoring the space station.
The Dragon spacecraft docked autonomously to the station’s Harmony module at 6:32 p.m. and opened that hatch about two hours later after pressurization and leak checks.
Kayla Barron, a Navy lieutenant commander who was added to the flight in May, was the first NASA astronaut to make her way into the station as mission control applauded.
The crew is joining three astronauts who are already on the space station – two Russians and NASA astronaut Mark Vande Hei.
"I can’t tell you how happy I am to see these smiling faces. All seven of us are friends and we’re going to become even better friends as time goes on," Vande Hei said during the welcome ceremony.
"It’s really an honor to be up here at the time when these folks arrived, to be able to help, not only to do science that’s going to help out humanity on earth right now, but also to help the human race be able to explore further and further away from our home planet."
The launch was originally supposed to launch on Halloween, but was delayed by bad weather and an undisclosed medical problem with a crew member.
It marks the fifth passenger flight for SpaceX, which was founded by Elon Musk in 2002.
Wednesday's launch carried the 600th person to ever reach orbit and comes just days after SpaceX returned four astronauts to Earth on Monday, bringing an end to a 200-day mission at the space station.
The Associated Press contributed to this report.