The group — called Working Canadians — is running radio ads in London and Kitchener-Waterloo and says it plans to expand its campaign to other markets.
Working Canadians spokeswoman Catherine Swift says the group, which was set up last month, believes the Ontario government is "quite beholden" to the unions.
During the last three elections, another group called the Working Families Coalition spent millions of dollars on advertisements attacking the Progressive Conservatives, helping the Liberals win.
Swift, who is also Chair of the Canadian Federation of Independent Business, says unions in the Working Families Coalition used dues collected from workers "to buy access at Queen's Park, resulting in higher taxes, debt and deficits."
The Working Families Coalition counters by saying it wants to stop "right-wing policies" that would force Ontario to compete with low-wage American states.