The primary settlement in town, where 1,301 people resided at the 2010 census, is defined by the U.S. Census Bureau as the Belmont census-designated place (CDP) and includes the densely populated portion of the town near the intersection of New Hampshire Route 106 and New Hampshire Route 140.
Originally known as Upper Gilmanton, Belmont was chartered in 1727 as a parish of Gilmanton. With water power from the Tioga River, it developed as a mill town. Built in 1833, the Gilmanton Village Manufacturing Co. made cotton and woolen textiles. Over the years it would change owners, names and products. In 1921, it was the Belmont Hosiery Co., a maker of silk, lisle and woolen stockings. It went out of business in 1955, and the renovated mill building is now a community center.
Separated from Gilmanton by an act of legislature, the town was incorporated on 28 June 1859 as Upper Gilmanton. The name Belmont was adopted in 1869 to honor August Belmont, a wealthy financier who (it was hoped) would contribute to the nascent town, but he never acknowledged the act.
In 1874, the Boston, Concord and Montreal Railroad passed through the northwestern section of Belmont, and service by the Franklin and Rochester Railroad was being planned.