Son of Benjamin Sheftall, his father was one of the original settlers in the new colongy of Savannah, arriving in 1733. His father married his mother, Perla in 1734, but sadly she passed away in 1738. His father then married Hannah Solomons and had several children. In 1756, Mordecai bought land for cattle raising and by 1760 he had purchased a warehouse and wharf on the Savannah River.In 1771 he married Frances Fannie Hart. Mordecai provided the community with land for its first Jewish cemetery and became a founding subscriber to Congregation Mickve Israel in Savannah. He was the Jewish representative among the original five incorporators of the Union Society, a non-denominational philanthropic association formed by Savannah's religious organizations to assist widows and poor children. In 1778 after having served as Commissary General of Georgia, General Robert Howe appointed him to the post of Deputy Commissary General to the federal troops stationed in Georgia and South Carolina. But before Congress could confirm his role he was captured in December 1778, along with his fifteen-year-old son, Sheftall Sheftall, in the battle to prevent Savannah from falling to British troops. Some of the outnumbered patriots escaped by swimming across the Savannah River, but the younger Sheftall could not swim and is father would not abandon him. With 185 other Americans, they were captured and imprisoned. He spent the remainder of the war in Philadelphia, working to help both the American cause and his own financial condition by financing a privateer to capture and loot British vessels. Sadly his investments did not work, and on its very first voyage, the ship ran aground. When the war ended in 1783 he returned with his wife and children to Savannah where his family resumed life for several generations. The state of Georgia granted him several hundred acres of land in recognition of his sacrifices on behalf of independence. He died in 1797 at the age of 62 and his beloved home city of Savannah buried him with full honors in the Jewish cemetery he created.