Lines in many places began forming at 7am local time (14:00 GMT) when booths opened for Californians first to decide whether to oust Democrat Davis, and then pick from an assortment of 135 candidates, including the Republican bodybuilder-turned-actor.
Schwarzenegger arrived at his local polling station through a back entrance where a polling worker, saying she hated to be rude, asked him for his name before he cast his ballot shortly after 9am (1600 GMT).
Schwarzenegger slipped on a pair of brown frame glasses to scrutinise the ballot before voting, and later said he found himself among the 135 listed candidates by looking for the longest name.
"I feel good," he told reporters. "I'm going to spend some time with my family, and then I'm going around thanking people ... all the people who worked so hard on this campaign. We worked hard, and we campaigned hard to try to get the message out," he said. "We hope for the best.
Although results were expected Tuesday night after polls close at 8pm (03:00 GMT), it could be weeks until the state certifies the official result. Some observers held out the prospect of a recount or a court challenge if the vote proves especially close.
What began as a Republican-led protest vote over Davis' handling of the state's economy and recent energy crisis has become a referendum on Schwarzenegger, especially his alleged groping and sexual harassment of women.
Governor Gray Davis is widely
blamed for state's poor finances
Davis' wife Sharon campaigned for her husband at the last minute, once again bringing up claims of impropriety against Schwarzenegger, who in turn has accused the Davis campaign of dirty tricks in the crucial final days before the recall.
In Washington, President George Bush praised Schwarzenegger for running a "spirited" campaign and pledged to work with the actor if he wins.
"If he's the governor I'll work with him - absolutely," Bush told reporters after a Cabinet meeting. "He's obviously waged a spirited campaign. He has captured a lot of people's imaginations."
Davis' campaign said its new tracking survey of 1200 likely voters found a 50% to 48% split between those favouring a "yes" vote on the recall and those planning to vote "no".
That survey was at odds with the latest numbers from the Schwarzenegger camp, which found 55% in favour of the recall and just 36% opposed, although the actor's handlers said only 250 people were polled on Monday.