Kelly and Russian cosmonauts Mikhail Kornienko and Sergey Volkov landed late Tuesday night in the Kazakhstan desert, NASA and Russian mission control said.
Kelly could be seen pumping his fist and giving a thumbs up after being hoisted from the Russian Soyuz spacecraft that brought the trio back.
All three underwent field tests immediately after leaving the spacecraft.
Kelly has completed a nearly yearlong mission on the International Space Station, the longest any U.S. astronaut has been in space.
Spending 340 days in space could affect a person's vision and bones, but Kelly said last week that physically, he feels pretty good. "I could go for another 100 days or 100 years," the astronaut said during his last briefing with reporters from orbit.
But the long stay has also been lonely. "The hardest part is being isolated from people on the ground who are important to you," he said.
But the long stay has also been lonely. "The hardest part is being isolated from people on the ground who are important to you," he said.
The space veteran said he has witnessed some of the most amazing scenes of Earth during his mission, like spotting the northern lights, passing over the Bahamas and watching huge storms like Hurricane Patricia.
