Fremont is a city in and the county seat of Sandusky County, Ohio, United States, along the Sandusky River. It is about 35 miles southeast of T…Fremont is a city in and the county seat of Sandusky County, Ohio, United States, along the Sandusky River. It is about 35 miles southeast of Toledo and 25 miles west of Sandusky. The population was 15,930 at the 2020 census.