Outgoing International Space Station (ISS) commander Shane Kimbrough along with Russian crewmates Sergey Ryzhikov and Andrey Borisenko were scheduled to wrap up a 173-day mission on Monday, with a parachute landing in Kazakhstan at 7:21 a.m. EDT (1121 GMT).
The astronauts exchanged hugs and took photographs before closing the hatch door on the ISS.
Their replacements, NASA's Jack Fischer and Fyodor Yurchikhin of Roscosmos, were due to arrive on April 20 at the station, which is in orbit about 250 miles (400 km) above Earth.
The US and Russian space agencies last week agreed to extend Peggy Whitson's mission by three months to fill in as the new crew's third member as well as the current mission commander.
For Whitson, 57, it was her second stint in charge of the $100 billion station, a multinational project overseen by the National Aeronautics and Space Administration and the Russian space agency Roscosmos.