Henry Van Rensselaer was born at the manor house in Albany, New York. He was the son of Stephen Van Rensselaer III, who was also a Representative and founder of the Rensselaer Polytechnic Institute. Henry graduated from the United States Military Academy at West Point, New York in 1831. He was appointed a brevet Second Lieutenant of the Fifth Regiment, United States Infantry on July 1, 1831, and resigned January 27, 1832. He then engaged in agricultural pursuits near Ogdensburg, New York, and served as a military aide to Governor William H. Seward from 1839 to 1840.