John Imlay was born in New Sharon, Pennsylvania, on December 18, 1749, the son of Johnston Imlay and Isabella Montgomery. After his father's death in 1763, he took charge of the family's wheelwright business. By 1776 he had moved to Philadelphia, where he became a successful merchant, primarily interested in the Caribbean trade. In 1783, he moved to Allentown, New Jersey, where he lived until his death in 1813. He married Elizabeth De Bow on January 25, 1773, and they had twelve children, including John Imlay, Jr. Following Elizabeth's death, John Imlay, Sr., married Ann Cafferty. John Imlay, Jr., lived in St. Thomas, Virgin Islands, and also worked as a merchant.