Wauseon is the county seat of Fulton County. Residents named the town in honor of Wauseon, a Potawatomi Indian chief. Although the Ohio legislature established Fulton County in 1850, Wauseon did not become the county seat until 1870. The village formed in 1854, and E.L. Hayes constructed the town's first building.
Wauseon grew quickly, attaining a population of 1,905 people in 1880. In 1886, twenty-five percent of the town's residents were school-aged children. The city contained three newspaper offices, six churches, and one bank. Most Wauseon businesses either processed crops or sold agricultural implements to the farmers in the neighboring countryside.
The same held true for the twentieth century. In 2000, Wauseon was Fulton County's largest population center, with 7,091 residents. In the past several decades, thousands of residents of nearby Toledo, Ohio, have moved to Wauseon or other parts of Fulton County, hoping to escape the larger city's busyness.