Whitson was originally scheduled to return from the space station in June, but extended her stay to take advantage of a later opening in Russia's space schedule.
As a result of the impacts of Hurricane Harvey, NASA is reviewing return plans to Houston.
The crew will participate in standard post-flight medical evaluations. Her just-concluded mission lasted 288 days.
Peggy Whitson has spent a total of 665 days in space during her career, more than any other American astronaut.
Back at the space station, NASA astronaut Randy Bresnik, European Space Agency astronaut Paolo Nespoli and Russian cosmonaut Sergey Ryazansky will be the only three crewmembers on board until September 12, when the Expedition 52/53 crewmembers arrive.
Whitson, a biochemist, set a breakneck pace on all three of her space station expeditions.
Whitson and two other astronauts landed in Kazakhstan late Saturday, U.S. time.
Thousands of Rohingya Muslims cross over to Bangladesh amid fresh violence
The UN believes those operations may have amounted to ethnic cleansing of the Rohingya - allegations denied by the army. Sahany said many crossed "with bullet injuries and burn injuries". "People are traumatised, which is quite visible".
She became the world's oldest spacewoman, at age 57, and the most experienced female spacewalker, with 10, following her launch last November. The other astronaut to return home was Jack Fischer, with 136 days in orbit.
The station's newest commander, Randy Bresnik, noted the outpost was losing 1,474 days of spaceflight experience with the departure of Whitson, Yurchikhin and Fischer.
Yurchikhin returned to Earth with a total of 673 days in space on his five flights, putting him in seventh place on the all-time endurance list.
With all three seats filled, the Soyuz MS-04 spacecraft undocked from the space station's Poisk module at 5:58 p.m. EDT (1758 GMT), kicking off the crew's 3-hour and 24-minute journey back to Earth. I love working up here.
"Trust me, you don't want to know the details", she said via email in response to questions from The Associated Press.
Russia's Soyuz MS-04 spacecraft with three crew members on board is performing a retrograde burn to ensure proper velocity and positioning for a safe landing, a Russian Mission Control center official told TASS on Sunday.
During the interim, thanks to Whitson's extended mission, USA research that otherwise would have been sharply curtailed was able to continue.
- Trump to Promote Tax Reform
- Harvey-displaced Houston Astros lose 'home' game in Florida
- Sudbury District Health Unit has human case of West Nile Virus
- Islamic Society to collect for Harvey victims during Eid al-Adha observance
- Moscow stands against amendment of Iran nuclear deal provisions
- Animal Ag Alliance on Help for Farmers Hit by Harvey
- Weather Forecast: Very hot Labor Day weekend
- Jets strike as Isis convoy flees border siege
- Pentagon notifies US Congress of $593 million military sale to Nigeria
- North Korea missile threat: U.S. diplomatic efforts failed, Fmr. Navy SEAL says