Oneonta Armory is a historic National Guard armory building located at Oneonta in Otsego County, New York, built in 1905 with a brick and stone castle-like structure. It was designed by State architect George L. Heins. It consists of a two-story administration building with an attached drill shed. The building features a 5-story octagonal tower at the southwest corner and a 2 1/2-story square tower at the northwest corner. It was listed on the National Register of Historic Places in 1995.