The Democratic governor said that he and his wife Gwen tested positive Monday night following a PCR test after initially testing negative for the virus earlier that morning.
Their son had tested positive after having "some sniffles over the weekend," the governor said in a video Tuesday.
Walz said in a statement that his son currently has "mild symptoms," while he and his wife are not experiencing symptoms.
"As a dad, I'm super concerned obviously for my family, but everybody is doing well," he said in the video.
The governor, 57, said he and his wife are fully vaccinated and boosted, and that their son is vaccinated, adding that "I am confident that these vaccines are protecting my family and me from serious illness."
Walz and his family are isolating as he continues to work from home. He encouraged Minnesotans vaccinated and boosted against Covid-19 and get tested ahead of the holidays.