Montgomery County is a county in the U.S. state of New York. As of the 2020 census, the population was 49,532. The county seat is Fonda. The county was named in honor of Richard Montgomery, an American Revolutionary War general killed in 1775 at the Battle of Quebec. The county is part of the Mohawk Valley region of the state. The county is part of the Albany-Schenectady-Troy combined statistical area.