Van Cortlandt was born in 1728 in British America. He was the second son of prominent New York merchant and landowner Frederick Van Cortlandt and Frances ( Jay) Van Cortlandt (1701–1780). His elder brother was James Van Cortlandt (who also married a daughter of Mayor Cornelis Cuyler). His younger siblings were Frederick Van Cortlandt II (who did not marry), Anne Van Horne (who married Nathaniel Marston III and Augustus Valette Van Horne), Eva Van Cortlandt (who married Henry White).
