Pierrepont was born on September 2, 1849, in Rye, New York into a prominent Brooklyn family that helped found Green-Wood Cemetery.
[5] His paternal grandparents were the merchant, farmer, landowner and land developer Hezekiah Pierrepont and Anna Maria Constable (a daughter of Anna White and William Constable of Philadelphia).
[4] His maternal grandparents were Peter Augustus Jay (eldest son of Gov.
Following his father's retirement, John with his elder brother Henry took over Pierrepont Stores, the family import-export and warehouse business.
In 1895, the brothers sold Pierrepont Stores to Brooklyn Wharf and Warehouse Company.