Then he studied law in the office of Hugh Maxwell, but soon abandoned this and became a merchant instead.
On March 30, 1836, he married Elvira Lynch Aymar (1817–1898), and they had four children, among them State Engineer John D. Van Buren Jr. (1838–1918).
Van Buren was a member of the New York State Assembly (Orange Co., 1st D.) in 1863.
Horatio Seymour as Paymaster-General of the State Militia, with the rank of colonel, and remained in office until the end of 1864.
Van Buren died "suddenly of apoplexy," and was buried at the Woodlawn Cemetery in New Windsor, New York.