Millersburg is the county seat of Holmes County. In 1824, Charles Miller and Adam Johnson surveyed the town. The town became the county seat the following year.
The town grew slowly, having only 673 residents by 1840. In 1844, a fire erupted in the town, destroying much of Millersburg. In 1846, the village contained four churches, two newspaper offices, thirteen stores, one iron foundry, and one grist mill. Over the next forty years, Millersburg’s population tripled in size, having a population of 1,814 people in 1880. The town consisted of two newspaper offices, seven churches, two banks, and several additional manufacturing businesses. The town’s largest employer was Henry Snyder, a tile manufacturer, who employed twelve workers. Most businesses provided materials to farmers in the surrounding countryside or processed the farmers’ crops. The same remains true today. In 2000, Millersburg’s population was 3,326 people, making it the sixth largest urban center in Holmes County.