Their capsule parachuted into the Gulf of Mexico off the coast of Pensacola, Florida, in darkness. Recovery boats quickly moved in with spotlights.
Their homecoming -- coming just eight hours after leaving the International Space Station -- paved the way for SpaceX's launch of their four replacements as early as Wednesday night.
The newcomers were scheduled to launch first, but NASA switched the order because of bad weather and an astronaut's undisclosed medical condition. The welcoming duties will now fall to the lone American and two Russians left behind at the space station.
Before Monday afternoon's undocking, German astronaut Matthias Maurer, who's waiting to launch at NASA's Kennedy Space Center, tweeted it was a shame the two crews wouldn't overlap at the space station but "we trust you'll leave everything nice and tidy." His will be SpaceX's fourth crew flight for NASA in just 1 1/2 years.
NASA astronauts Shane Kimbrough and Megan McArthur, Japan's Akihiko Hoshide and France's Thomas Pesquet should have been back Monday morning, but high wind in the recovery zone delayed their return.
"One more night with this magical view. Who could complain? I'll miss our spaceship!" Pesquet tweeted alongside a brief video showing the space station illuminated against the blackness of space and the twinkling city lights on the nighttime side of Earth.
From the space station, NASA astronaut Mark Vande Hei -- midway through a one-year flight -- bid farewell to each of his departing friends, telling McArthur "I'll miss hearing your laughter in adjacent modules."
Before leaving the neighborhood, the four took a spin around the space station, taking pictures. This was a first for SpaceX; NASA's shuttles used to do it all the time before their retirement a decade ago. The last Russian capsule fly-around was three years ago.
It wasn't the most comfortable ride back. The toilet in their capsule was broken, and so the astronauts needed to rely on diapers for the eight-hour trip home. They shrugged it off late last week as just one more challenge in their mission.
The first issue arose shortly after their April liftoff; Mission Control warned a piece of space junk was threatening to collide with their capsule. It turned out to be a false alarm. Then in July, thrusters on a newly arrived Russian lab inadvertently fired and sent the station into a spin. The four astronauts took shelter in their docked SpaceX capsule, ready to make a hasty departure if necessary.
Among the upbeat milestones: four spacewalks to enhance the station's solar power, a movie-making visit by a Russian film crew and the first-ever space harvest of chile peppers.
The next crew will also spend six months up there, welcoming back-to-back groups of tourists. A Japanese tycoon and his personal assistant will get a lift from the Russian Space Agency in December, followed by three businessmen arriving via SpaceX in February. SpaceX's first privately chartered flight, in September, bypassed the space station.