Hardenbergh was descended from a Dutch family that settled New Amsterdam in the seventeenth century and was prominent in New York colonial affairs. He prepared for ministry at the home of the Reverend John Frelinghuysen, a prominent Dutch Reformed minister near Somerville, New Jersey. After being ordained, Hardenbergh was called to serve congregations in New Jersey's Raritan River valley, and later in Ulster County, New York. During the 1760s, Hardenbergh was influential in the establishment of Queen's College, the eighth of nine colleges established during the colonial period. After his efforts to lobby Britain's King George III and New Jersey's royal governor, William Franklin to permit the establishment of a Dutch Reformed-affiliated college, Queen's College was chartered in 1766. During the American Revolution, Hardenbergh served as a delegate for New Jersey's Provincial Congress which ratified the Declaration of Independence and to frame the state's first constitution (1776). He subsequently served several successive one-year terms in New Jersey's General Assembly. In 1785, Hardenbergh was appointed as the first president of Queen's College, a post he would hold from 1786 to his death in 1790.