A list of Ohioan companies. Many well known Ohio companies have been included. While this list isn't definitive, these are most of the top businesses in the state of Ohio. As a country, the United States has encouraged entrepreneurship throughout much of its history. The state of Ohio is no exception to this rule, and new businesses are started in Ohio daily, ranging from corporations to LLCs to partnerships to sole proprietorships. This list, however, is mostly focused on the largest corporations in the state of Ohio.