The pair met for a joint media conference, held outdoors at the Botanical Garden, to announce a new partnership between the state and New Zealand, on climate change.
Governor Gavin Newsom tweeted about his positive result Saturday afternoon (US time).
"This AM, I tested positive for Covid-19 and am currently experiencing mild symptoms. Grateful to be vaccinated & for treatments like Paxlovid," he said.
Newsom said he was following health directives and would be working remotely while he isolates.