Born Eliza Lucas in 1722, she was the daughter of the British governor of the colony of Antigua. Her family moved in 1739 to the colony of South Carolina in hopes that the change of climate would improve Eliza's mother's health, but Lt. Col. Lucas shortly thereafter had to return to Antigua due to conflicts between England and Spain. Eliza stayed and ran the Carolina plantation, since her mother couldn't; she was the first great experimenter in agriculture in America and introduced the cultivation of indigo to South Carolina, which became a great cash crop until the American Revolution (second only to rice; cotton was not much grown in the American South until the cotton gin was invented after the American Revolution).

In 1744 she married widower Charles Pinckney, the Chief Justice of the province. In the fourteen years before he died, they had three children: Charles Cotesworth Pinckney, Thomas Pinckney, and Harriott Pinckney (later Mrs. Daniel Horry). Charles C. was an American general during the Revolution and signer of the U.S. Constitution; Thomas was also an officer on the U.S. side of the Revolution and later the U.S. minister to Spain and Great Britain and governor of South Carolina (and married the daughter of Rebecca Motte); and Harriott saved General Francis Marion's life (he had taken refuge at her house when the British were pursuing him; when the soldiers were heard approaching she was able to hid Marion while the British officer ate the meal that had been fixed for Marion). Mrs. Pinckney continued to manage the plantations while her husband was working and after his death.

The war ruined her financially, but her children were able to support her. She died in 1793 and was so well regarded that George Washington served as one of her pallbearers.