When Pierre Theriot was born on 23 February 1877, in Saint Martinville, St. Martin, Louisiana, United States, his father, Pierre Adonis Theriot, was 22 and his mother, Clementine Barras, was 31. He married Marie Genevieve Lopez on 6 October 1900, in St. Martin, Louisiana, United States. They were the parents of at least 3 sons and 4 daughters. He lived in Police Jury Ward 3, St. Martin, Louisiana, United States for about 10 years and Police Jury Ward 1, St. Martin, Louisiana, United States in 1940. He died on 1 January 1952, in Saint Martinville, St. Martin, Louisiana, United States, at the age of 74, and was buried in Saint Martinville, St. Martin, Louisiana, United States.