Early settlers came to the Dry Brook Valley of Hardenburgh in 1800, and in 1859 the Town of Hardenburgh was separated from Shandaken and established from the Towns of Denning and Shandaken. The town was named for Johannes Hardenburgh, a landowner. Early industries in the area included lumber and saw mills, as well as agriculture, especially cauliflower.
Five of the Catskill High Peaks are within or along its borders. Today, there is no town-center of Hardenburgh, and the rural town consists only of homes and farms. In fact, because of the mountains, the only direct route from Hardenburgh to the rest of the county are hiking trails over them. Drivers must go through either Sullivan or Delaware counties. Hardenburgh is a great area for hiking and fishing. Hardenburgh has the smallest population of all Ulster county towns.