"The suspect must be arrested until February 8, 2020," the judge said on late Friday, as broadcast by the UNN news agency.
In the early hours of Saturday, the court also decided to arrest Ukrainian serviceman Andriy Antonenko until the same date over suspected links to the murder.
On Friday, one more suspect, military doctor Yana Dugar, was placed under house arrest.
Sheremet, who worked for various Russian and Ukrainian media outlets, died in a car explosion on July 20, 2016, in the Ukrainian capital.
On Thursday, Ukrainian Interior Minister Arsen Avakov said that five people were suspected of having links to the murder. Three of them have been detained.
In 2017, reporter Pavel Sheremet was added to the Journalists Memorial in Washington, DC along with another 13 reporters.