In keeping with his message of austerity and painful choices, the veteran Democrat, who was the state's governor for two terms from 1975 to 1983, served hot dogs at his inaugural lunch after taking over from Republican Arnold Schwarzenegger.
Inheriting a budget gap estimated at nearly $28 billion through mid-2012, Brown has called for more spending cuts to balance the books in California, the state with the largest population and worst credit rating.
He is also widely expected to push for a special election that would ask voters to extend temporary tax increases to help balance the state's books.
Brown must present the Democratic-controlled state legislature with a budget plan for the fiscal year beginning in July within a week. He said the plan he would present would be painful.
"At this stage in my life, I have not come here to embrace delay and denial," Brown told an audience in Sacramento, the state capital, after taking the oath of office.
Brown also pledged to make environmental issues a top priority and said he intended to meet his goal of bringing 20,000 megawatts of energy from renewable sources online by 2020.
State Democrats recently rejected Schwarzenegger's plan to close a roughly $6 billion shortfall in the current fiscal budget. They said they would wait to work on the budget with Brown.
FOLLOWS IN FOOTSTEPS
With California's low credit rating under pressure due to the budget shortfall, analysts expect Brown to follow through with spending cuts that affect all parts of the state government.
"I think there is a lot of pain that is going to be shifted around," said Howard Cure, director of municipal research at Evercore Wealth Management in New York.
"For a lot of states, I think this is going to be the toughest year," Cure added. "I don't think the federal government is going to be there to help."
Brown, whose father also served as California's governor, became the state's oldest governor on Monday. During his inaugural address Brown joked about his age, noting he was once more following in his father's footsteps -- and his own.
He made headlines in the 1970s when, as a first-term governor, he dated singer Linda Ronstadt and espoused unconventional ideas, prompting a columnist to dub him "Governor Moonbeam."
The nickname and reputation as a dreamer stuck, helping sink his bids for a U.S. Senate seat and his party's presidential nomination. His political career appeared at a dead end until he was elected mayor of Oakland, California, in the 1990s, paving the way for a comeback to statewide office.
Brown, who most recently served as the state's attorney general, easily defeated Republican challenger and former eBay Inc Chief Executive Meg Whitman in the November gubernatorial election. Schwarzenegger was barred from seeking a third term due to term limit laws.
