The governor’s office said in a statement that Northam is showing no symptoms while those of Pam Northam are mild.
Northam and his wife plan to isolate for the next 10 days while working remotely.
Northam, a Democrat, is the country’s only governor who is also a doctor. Some Republican lawmakers criticize his restrictions aimed at slowing the spread of the coronavirus, calling them too stringent.
Northam said in a statement that the positive test result shows that the virus is “very real and very contagious.”
“We are grateful for your thoughts and support, but the best thing you can do for us — and most importantly, for your fellow Virginians — is to take this seriously,” Northam said.
The governor and first lady were notified Wednesday that a member of the Executive Mansion staff also had tested positive for the virus.
Three other governors also have tested positive for COVID-19, though one of those turned out to be a false positive.
Earlier this week, Missouri Gov. Mike Parson, a Republican, announced he’d tested positive.
Oklahoma Gov. Kevin Stitt in July became the first governor to announce he’d tested positive. He recovered and returned to work less than two weeks later.
In August, Ohio Gov. Mike DeWine announced that a rapid test was positive. But a short time later, DeWine said a more sensitive test was negative.
Northam’s announcement that he tested positive for the virus comes on the same day as a planned rally by President Donald Trump in Newport News, an event the governor’s staff has asked to be canceled, re-scheduled or scaled down because of concerns about the virus.
The event is expected to draw 4,000 people, which would violate Northam’s executive order generally banning gatherings of more than 250 people.
The Trump campaign has routinely flouted public health guidelines intended to halt the spread of COVID-19.