Branchville is a borough in Sussex County, New Jersey, in the United States. As of the 2010 United States Census, the borough population was 841. The borough is located in the northernmost region of Sussex County.
Branchville was incorporated as a borough by an Act of the New Jersey Legislature on March 9, 1898, from portions of Frankford Township. An additional portion of Frankford Township was annexed as of March 1, 1951.
Branchville was established by settlers from Connecticut in the 18th century. It grew quickly and in the 1820s the town was divided into building lots. By the year 1844, Branchville was a well established community with 32 dwellings, mills, blacksmiths, an academy, a church and a variety of other factories and businesses.