The 10-minute audience with the British monarch is a tradition that marks the official start of the campaign for the general election set for May 7.
Speaking after the call-on outside the famous 10 Downing Street black door, Cameron urged Britain's voters to keep him in power for a second five-year term.
"I want to see the job through," said the 48-year-old leader of the Conservative party, who has led a coalition government alongside the Liberal Democrats.
He went on to promise to campaign in "all four corners of all four nations (England, Wales, Scotland and Northern Ireland) of the UK" during the next 38 days.
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The election, he said, was "about moving forward after five years of effort and sacrifice".
Under UK election rules, government ministers remain in charge of their departments until a new administration is formed, but MPs cease to be members of parliament and writs will be issued for elections in all 650 constituencies.
Issues likely to dominate this year's campaign include the economy and spending cuts, Britain's EU membership, the future of the National Health Service and immigration.
If Cameron is re-elected, he has promised to deliver an EU membership referendum by the end of 2017, raising the prospect of Britain leaving the world's largest trading bloc.
Coalition partners Liberal Democrats, meanwhile, are urging the voters to avert a swing to the Left (Labour) or the Right (Tory). Deputy Prime Minister and Liberal Democrat leader Nick Clegg said his party would occupy the "reasoned centre ground" during the campaign.