Speaking at the Welsh Conservative conference in Llangollen, Cameron said that Britain will see "real opportunities for growth" in key sectors like digital and energy and services if it remains part of the EU, Xinhua reported.
"We'll be in that EU Single Market with easy access to the 500 million consumers that it brings," he said.
"We'll keep the 100,000 jobs that are linked to Welsh access to the single market, and we'll have a special status that keeps us out of the parts of Europe that we don't need -- out of the euro, out of the open borders, out of 'ever closer union'," the prime minister elaborated.
Cameron also highlighted the risks to British trade if the country leaves the EU.
"If we left the single market and relied on World Trade Organisation rules, some suggest the extra costs of exporting British beef would be 240 million pounds ($345 million) a year," he noted.
A Canadian-style free trade deal with the EU, proposed by some Eurosceptics, had taken seven years to negotiate and could still face uncertainty, he stressed.
"Think about that. Seven years of uncertainty for businesses not knowing what the arrangements would be for trading with Europe," he warned.
"Those seven years of uncertainty -- they cannot be justified, they can't be in our national interest and we should reject that idea out of hand," the prime minister noted.
However, London mayor Boris Johnson, a leading advocate of Britain leaving the EU, on Friday argued that a Brexit would be a "win-win for all".
Speaking at a political gathering in Kent, Johnson said that the EU "is going in the wrong direction".
"It is time for real reform. The only way to get that is to leave," he said.
He insisted that Britain "will continue to grow and prosper and thrive as never before" if it votes to leave in June.
"You look at the (EU) plan to increase the efforts to prop up the single currency with an ever denser system of integration, with more and more regulation about all sorts of social and economic issues which will impact directly on this country, I think the risk is increasingly in staying in the project," he told his audience.
Britain will hold a referendum on whether to remain in the EU on June 23. The British government's official position is that Britain should stay in a reformed EU.