Johnstown is a city and the county seat of Fulton County in the U.S. state of New York. As of the 2010 Census, the city had population of 8,743. The city was named by its founder, Sir William Johnson after his son John Johnson. Sir WIlliam Johnson was a baronet and officer in the British army.. The city of Johnstown is mostly surrounded by the town of Johnstown, of which it was once a part when it was a village. Also adjacent to the city is the city of Gloversville.