Washington
The crew's SpaceX Dragon Capsule splashed down just south of Pensacola on Florida's Gulf coast, the BBC reported.
The successful end to the crew's mission initiates a new era for the American space agency.
All its human transport needs just above the Earth will in future be purchased from private companies, such as SpaceX.
The government agency says contacting out to service providers in this way will save it billions of dollars that can be diverted to getting astronauts to the Moon and Mars.
Hurley's and Behnken's capsule touched the water shortly after 14.45 EDT (19.45 BST; 18.45 GMT).
The sight of the vehicle's four main parachutes floating down over the Gulf of Mexico was confirmation the spacecraft had survived its fiery descent through the atmosphere.
Recovery vessels are now working to make the capsule safe and lift it out of the water. The astronauts will then be able to get out.
The men will be checked over by medical staff before being flown to shore by helicopter.
The astronauts' Dragon capsule launched to the space station at the end of May on a Falcon 9 rocket, also supplied by SpaceX.
Their mission served as an end-to-end demonstration of the astronaut "taxi service" the company, owned by tech entrepreneur Elon Musk, will be selling to Nasa from now on.
The Boeing corporation is also developing a crew capsule solution but has had to delay its introduction after encountering software problems on its Starliner capsule.
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