The governor said he had issued an executive order authorizing the distribution of an $100 million to cities and counties across California to blunt the impact of the respiratory illness on the homeless, and had acquired 1,300 trailers to use as temporary housing.
Stuart Malcolm, a doctor with the Haight Ashbury Free Clinic, speaks with homeless people about COVID-19 in the Haight Ashbury area of San Francisco on March 17, 2020.
Essential services such as pharmacies, gas stations, banks, laundromats and places offering food - such as grocery stores, food banks, farmers markets, convenience stores and eateries with takeout or delivery - are allowed to remain open.
Bars, nightclubs, theaters, gyms and convention centers have been ordered closed.
The governor said he hopes people will voluntarily obey the order to stay at home if possible, saying, "There's a social contract here".
California, which has a population of around 40 million, appears to be the first state to order restrictions statewide.
Earlier in the day, it was stated in a letter to President Donald Trump, Newsom warned the president that roughly 56% of the California population will be infected with the virus over an 8-week period. "We need to meet this moment and flatten the curve together". "But there is a subset that we're concerned about" who will be more seriously affected.
As of Thursday evening, the state had seen 952 confirmed cases and 18 deaths, according to Johns Hopkins figures.