NY 205 originally began at NY 23 northwest of Oneonta when it was assigned as part of the 1930 renumbering of state highways in New York. The route originally followed local, substandard roads surrounding Otego Creek; however, it was gradually moved onto its modern alignment over the course of the 1930s. It was officially extended southward from West Oneonta to connect to I-88 in 1970; however, it was not extended southward in reality until the mid-1970s. The extension created a short overlap with NY 23 west of the city.