The Starliner undocked as scheduled at 6:04 p.m. EST on Friday, according to a NASA livestream.
Astronauts Barry "Butch" Wilmore and Sunit "Suni" Williams will remain on the ISS for another six months before returning to earth on a regular space station crew rotation.
NASA said cargo returning on the uncrewed Starliner includes hardware, completed experiments, and items no longer needed by the Crew Flight Test astronauts.
Starliner's deorbit burn is scheduled for 11:17 p.m. EST and the spacecraft is scheduled to land at the New Mexico SpacePort on Saturday.
The troubled spacecraft suffered malfunctions to five of its 28 maneuvering thrusters and five separate helium leaks on its ascent to the ISS on June 5.
No date has been announced for another manned flight of the Starliner, but NASA officials plan to study it carefully and are considering part redesigns.