His father was the only surviving son of Jacobus Van Cortlandt, the 30th and 33rd Mayor of New York City, and the former Eva de Vries Philips.

[5] After his elder brother James died in 1781, Augustus inherited his father's fieldstone and brick Georgian style manor, the Van Cortlandt House.

[6] The estate remained in the family until 1889 when they sold the property to the City of New York as part of Van Cortlandt Park's creation.

In 1753, Van Cortlandt succeeded John Chambers to become Clerk of the City[8] and County of New York,[9] of which he was the last under British rule.

[10] During the Revolutionary War, Van Cortlandt "hid city records from the British by storing them in Vault Hill" on his family's estate in February 1776.

Augusta married Dr. Edward Newenham Bibby and Helen married merchant Abraham Schermerhorn and was the mother of Caroline Webster Schermerhorn (1830–1908), who was well known in New York society during the Gilded Age for her marriage to William Backhouse Astor Jr.[19] Through his daughter Helen, he was a grandfather of Augustus Frederick Morris (1797–1859),[1] who also assumed the surname of Van Cortlandt to inherit a part of his grandfather's estate in Lower Yonkers.