Newsom's plan includes $13.6 billion to boost reserves and pay down debt and pension liabilities.
Newsom said such measures were meant to ensure that the state remains on sound fiscal footing to "make the California dream available to all".
Including bonds and special funds the total budget is $209 billion.
Newsom plans to deliver on his promise Thursday at a news conference discussing his proposal in detail.
Newsom has already outlined more than $2.5 billion in spending proposals focused on early childhood education and health care. He's framed his budget as a "California for All" agenda that looks to close the gaps between rich and poor.
The nonpartisan Legislative Analyst's Office has projected that the state's "rainy day fund" constitutional budget reserve will reach almost $15 billion by the end of the 2019-20 fiscal year.
The nonpartisan legislative analyst projected in November that lawmakers would have a $15 billion surplus to allocate next year on top of $15 billion in the rainy day fund, which is at the maximum allowed under the state Constitution.
"I'm about to announce an interesting surplus - that will be a little more interesting than the one you've been reading about or writing about", he told reporters after announcing new wildfire prevention efforts in Colfax on Tuesday.
"We're assuming we're going to continue the economic expansion", Newsom said during his budget presentation in Sacramento.
Among the budget items that Newsom has already outlined are a almost $2 billion plan to support low-income children, with much of the money earmarked for construction of childcare facilities and kindergarten classrooms. He says 86 percent of the new spending is for one-time investments. That would limit the long-term cost of his initiative and help Newsom maintain his pledge to preserve rainy day savings.
Helping low-income children in the crucial early years of life, when brains are developing rapidly, was a central campaign promise for Newsom, who has four young children and was elected with an overwhelming majority in November.
He proposed expanding state-funded health care to low-income people living in the county illegally until the age of 26.
Newsom also plans to increase subsidies for people who buy their own insurance, rather than getting it from an employer or government program. His health proposals would cost $760 million a year.
He also wants to expand the state's paid leave program and eventually increase it to six months of leave split between parents, although it is unclear how he would pay for a full six-month program.
California now replaces a portion of wages for six weeks for new parents, and birth mothers can take an additional six weeks of disability leave.
Former Gov. Jerry Brown tried to resurrect the program last fall as a voluntary tax, but that died in the Legislature as well.