Born into a prominent family in Charles Town in the Province of South Carolina, Pinckney studied in Europe before returning to America. He supported the independence cause and worked as an aide to General Horatio Gates. After the Revolutionary War, Pinckney managed his plantation and won election as Governor of South Carolina, serving from 1787 to 1789. He presided over the state convention which ratified the United States Constitution. In 1792, he accepted President George Washington's appointment to the position of minister to Britain, but was unable to win concessions regarding the impressment of American sailors. He also served as an envoy to Spain and negotiated the Treaty of San Lorenzo, which defined the border between Spain and the United States.