Sections of what is now NY 23 were part of unsigned legislative routes as early as 1908; however, NY 23 itself was not assigned until 1924. At the time, the route extended from Oneonta to Massachusetts and followed a slightly different alignment from Cairo to Claverack via Hudson that took the route along modern County Route 23B (CR 23B) in eastern Greene County. NY 23 was extended west to Norwich in the mid-1920s and to NY 26 in northwestern Chenango County in 1930. The route was gradually moved onto its current alignment between Cairo and Claverack in the 1950s and 1960s, and realigned on its western end in 1984 to serve Cortland County.