Meg Whitman, the billionaire former CEO of online auction firm eBay, will square off in the November general election against Democrat Jerry Brown.
With 13 percent of precincts reporting, Whitman, 54, had captured 64 percent of the Republican vote, while GOP rival Steve Poizner had 26 percent. Brown claimed his party's nomination with 84 percent of the Democratic vote.
Since declaring her intention to run on Feb. 9, Whitman virtually rewrote the rules of campaigning. She spent twice as much as any statewide candidate in primary history, starting her paid advertising campaign 14 months before the general election.
She joined U.S. Senate candidate Carly Fiorina in making history as they became the first women to win the California Republican Party's nomination to the state's highest elected offices.
She told supporters that Sacramento politicians now face their worst nightmare: "Two businesswomen who know how to create jobs, balance budgets and get things done."
Brown reminded his backers that "I've done this before."
"If we pull together we can fix things," he said. "I know how Sacramento works, and more importantly, I know how it should work."
Whitman entered the race promising to spend as much as $150 million of her own money on her campaign. By primary day, she had put in $71 million and raised another $16 million.
"From the beginning of the campaign, we built a plan and executed against it," said veteran Republican consultant Jeff Randle, a top Whitman adviser. "When the campaign got really ugly this year, we stuck to the plan. That's a complete reflection of who the candidate is."
The marketing expert rarely strayed from her script, rolling out catch phrases such as "spine of steel" and "the power of many" at her February 2009 campaign launch and repeating them at countless events in the following 16 months.
She also largely stuck to her three-pronged policy platform -- cutting government spending, fixing education and creating jobs.
Whitman showcased those messages when she started her radio campaign in September 2009 and began running TV ads in February, far earlier than any other statewide candidate.
"A good portion of her success has to do with the way she rolled out her campaign with virtually no opposition," said San Jose State University political science professor Larry Gerston. "Steve Poizner didn't spend during that period. That allowed her to start at a much more advanced level. It's really forced him to play a lot more catch-up ball than he might have."
The careful planning, which included hiring high-priced consultants tied to Gov. Arnold Schwarzenegger and former Gov. Pete Wilson, didn't stop the campaign from hitting bumps along the way.
Revelations about Whitman's poor voting history sent her campaign into a tailspin in September. She spent about two weeks apologizing for what she called an "atrocious" voting record, then began insisting that she recalled voting in "on numerous occasions" in elections for which no records currently are available.
Whitman's support also fell after Poizner began his paid advertising campaign slamming her ties to the maligned investment firm Goldman Sachs and staking a hard-right position on illegal immigration.
By May, Whitman's 50-point lead in a Public Policy Institute of California poll had shrunk to nine points.
Whitman responded by using her campaign's key advantage: money.
She filled the airwaves with new ads responding to the criticisms, rebuilding her lead. Poizner, another wealthy former Silicon Valley CEO, declined to match Whitman dollar for dollar.
Heading into the primary election, he had spent about $24 million of his own money on his campaign and raised $2.4 million from outside sources.