Susana Alexander was born in North Carolina on December 24, 1759. A great deal of contradictory evidence exists about Susana Alexander's early life and family. Susana herself states that her father's name was James Alexander. Other sources suggest that her last name was either Smart or Wilson, both of which were prominent Mecklenburg County families. Without definitive evidence such as a father's will or a marriage bond, it is impossible to say with certainly what her last name was. Consequently, editors have deferred to the maiden name of Alexander which Susana stated in her pension application.

Susana married John Alexander in Mecklenburg County on November 12, 1777. After their marriage, John Alexander went out in service as a private for the Patriot cause. He was away for at least nine months in 1779, though Susana later recalled that he was away in service for almost the entire length of the war.

In September 1780 while covering the troops retreating from Charlotte, Capt. Joseph Graham was knocked from his horse, attacked by British dragoons, and left for dead. Susana Alexander found Graham at a nearby spring, where he had dragged himself for water. She put him on her pony and brought him to her mother's house, where she hid the wounded captain overnight and tended to his wounds. The next morning, a British officer's wife visited the Alexander home. When she discovered that they were hiding a wounded Patriot officer, she offered to return with a British surgeon who could treat him. Fearing that they would take Graham prisoner, the Alexanders' alerted the captain's men, who helped evacuate him north behind Patriot lines where he could recover. (In one recollection, Susana also stated that she helped lead Graham through the woods during this evacuation.) Graham later credited Susana's efforts with saving his life.

When Susana's husband died on July 12, 1805, he and Susana had at least four children who were still living. Susana Alexander never remarried and continued to live within the confines of the Sugar Creek Congregation of Mecklenburg County for the rest of her life. A widow for over fifty years, she was affectionately known as "Aunt Susie" and worked as a midwife. She was a prominent member of the community, with one contemporary noting that "her aversion to [American] Indians [and] her fondness for her pigs" were well known.

In 1845 her reputation as a storyteller generated national attention when newspapers in Washington, DC challenged her story that future present Andrew Jackson and his mother had stayed at her family home while fleeing from British troops in the area during the revolution. Although she painted a colorful tale of "Ande Jackson," the young bow hunter who helped her tend to the family crops, Jackson's biographers disputed many of the details of her story, denouncing it as a tall tale. Newspapers also denounced her story about saving Joseph Graham, but several prominent citizens, including Graham's family, later vouched for her heroic efforts at saving the wounded officer.

In 1846 she applied for a widow's pension based on her husband's military service during the American Revolution, but did not attach enough requisite evidence to prove her claim. She renewed her efforts in 1851. This time she was endorsed by William Alexander Graham, the current U.S. Secretary of the Navy and the late Joseph Graham's son. This application was successful and she was granted $30 a year from 1831 until the time of her death. She died in Mecklenburg County on June 11, 1856.