“The Secretary is fully vaccinated and boosted against the virus and is experiencing only mild symptoms,” the department said in a statement.
Spokesman Ned Price said Blinken would no longer deliver a long-awaited speech on China policy scheduled for Thursday.
“He looks forward to returning to the department and resuming his full duties and travels as soon as possible,” the statement said.
Blinken has not seen President Joe Biden in person for several days and Biden is not considered a close contact, the State Department and White House said.
But Blinken earlier Wednesday met with Swedish Prime Minister Ann Linde at the State Department.
Blinken, who had tested negative a day before, took another test as he felt symptoms after meeting Linde, the State Department said.
Price said that all close contacts were being notified. Blinken also met Tuesday with Mexican Foreign Secretary Marcelo Ebrard and delivered a speech at the State Department on Latin America policy.
Blinken was among guests who packed into a Washington hotel on Saturday evening for the annual White House Correspondents’ Association dinner.
Trevor Noah, the comedian who introduced Biden, joked about the gala dinner being a “super-spreader” event.