McGuinty told farmers gathered for the International Plowing Match in Ayr that the government will introduce a Local Food Act to get their products into more places for consumers.
"If families dedicated just $10 more of their weekly foods budgets to buying Ontario products, it would generate $2.4 billion in economic activity and create 10,000 new jobs," he said.
"One of the things we want to put in place is a framework, and then develop some targets so we can measure ourselves against those targets."
The government will also make more of an effort to ensure Ontario-grown produce is available in the large, chain supermarkets, added McGuinty.
"I think one of the things that we're going to want to do is sit down with the big chains and figure out what we can do, working together, to ensure that every time you go into a store that is making food available, that there are foods that are marked from Ontario," he said. "Ideally locally-grown."
The Progressive Conservatives and New Democrats said they've been pushing the government for some time to adopt a buy-local policy when it comes to food.
"I'm hoping there are some firm targets for ministries that purchase food," said NDP Leader Andrea Horwath.
"I'm hoping that we're actually setting a real example here and not just playing up to the crowd."
Government statistics show each Ontario farmer produces enough food to feed 120 people a year.
McGuinty also raised the issue of the government's move to eliminate a $330-million share of slot machine revenues to horse tracks, but said the government was committed to ensuring a strong horse racing industry for the future.
A panel with former cabinet ministers from all three parties will gather feedback from the sector about how the government can help keep it going without the slot machine revenue, added McGuinty.
"We've engaged folks in the horse racing industry in a very important (consultation) and I think it's taken on a very thoughtful tone in terms of the discussion," he said.
"We know we can no longer support this industry the way we have in the past...but I'm convinced that we can take steps to put in place a stronger, viable and sustainable industry."
All of Ontario's political leaders and most MPPs attend the International Plowing Match each year to court the farm vote.