RNA - Limited access to the Capitol building and office buildings will begin at 5 p.m. EDT (2100 GMT) and last at least until April 1, the House and Senate Sergeants at Arms said in a statement. The Capitol Visitor Center will be closed and all public tours suspended.
Lawmakers, staff, credentialed journalists and visitors with official business would still be allowed entry.
Congress planned to take a week-long recess from Washington starting on Friday. But it was unclear when the break would start as lawmakers negotiated with the Trump administration over legislation to provide economic relief as the number of US coronavirus cases continued to grow.
Some members of Congress called for lawmakers to remain in Washington to address the health crisis.
Democratic US Senator Maria Cantwell said on Wednesday she would shutter her Washington office after one member of her staff tested positive for COVID-19.
Several other lawmakers also said they would be closing their offices in the US capital as a precautionary measure.
"Other congressional employees are likely to test positive in the days ahead," Senator Tom Cotton said in a statement, adding he expected disruptions would be minimal given Congress' scheduled week-long recess that is set to start on Friday.
Senator Mitt Romney also closed his Washington office, as did Senator Bill Cassidy.
Cassidy, a doctor, said his staff would begin teleworking. He expressed concern his youthful staff could be coronavirus carriers and not show symptoms, potentially spreading the disease to older visitors - who are at greater risk of complications from the illness - if his office remained open.
"I look at the demographics of who is working there, and who is visiting... and I don't think the twain should meet," Cassidy said on a conference call with journalists.
Senator Ted Cruz, who is among several lawmakers who have self-quarantined after coming in contact with someone who later tested positive for the coronavirus, also closed his Washington office.
Local offices in the members' home districts remained open.