Barca announced in a short statement that Umtiti is "asymptomatic, is in good health and is isolating at home."
Umtiti, 26, is currently sidelined with a knee injury and has not traveled with Quique Setien's squad to Lisbon for Friday's Champions League quarterfinal against Bayern Munich.
He had not been in contact with any of the Barca players in Portugal, who all returned negative results when tested for coronavirus ahead of the Bayern game this week.
Like Umtiti, he had not had contact with the first-team squad and is also asymptomatic and isolating at home.
There has been a surge in cases across Spanish clubs this week as teams returned for training, with the new La Liga campaign due to start on Sept. 12.
A La Liga spokesperson told ESPN the league remains focused on finishing the second division playoffs -- which have been delayed by coronavirus cases at Fuenlabrada, Real Zaragoza and Almeria -- and will then move ahead with plans to start the new season as planned.
"Of course we continue to monitor the COVID-19 situation closely and, as was the case with the restart back in June, we will do what we can to play in a safe, responsible way," the spokesman said.