In 1812, MacCarthy at the age of 48 married Antoinette Carpot, a French woman, the year he was appointed as governor of two former French territories in Africa. They had one son, Charles.
It was in 1812 that MacCarthy, then 48 years old, married Antoinette Carpot, a French lady, at the time when he received his appointment as governor of two African territories formerly owned by France. The couple had one child, Charles.