Herkimer County is a county in the U.S. state of New York. As of the 2020 census, the population was 60,139. Its county seat is Herkimer. The county was created in 1791 north of the Mohawk River out of part of Montgomery County. It is named after General Nicholas Herkimer, who died from battle wounds in 1777 after taking part in the Battle of Oriskany during the Revolutionary War. The county is part of the Mohawk Valley region of the state.