St. Bernard Parish contains a small community of Spanish descent. Sometimes referred to informally as "Spanish Cajuns", the Isleños are descended from Canary Islanders who arrived around 1780. This linguistically isolated group eventually developed its own dialect. This settlement was first called La Concepcion and Nueva Galvez by Spanish officials, but was later renamed Terre aux Boeufs (French) and Tierra de Bueyes (Spanish) for "land of cattle", because nearby areas were used for cattle grazing. By the end of the 1780s, St. Bernard, the patron saint of Bernardo de Galvez, was used in documents to identify the area.

The chief historical attraction in St. Bernard Parish is the Chalmette National Historical Park (or Chalmette Battlefield), at which the Battle of New Orleans took place on January 8, 1815 during the War of 1812. Many street names near the battlefield bear the names of the chief participants, or take a pirate theme, since the pirate Jean Lafitte was considered to be a hero in the battle. A high school, later elementary and now a middle school, was named in honor of (then Colonel) Andrew Jackson, who was the American commanding officer in the battle.

From 1919 to 1969, the parish was effectively ruled as part of the fiefdom of Leander Perez, a local Democratic official in neighboring Plaquemines Parish.

During the Great Mississippi Flood of 1927, New Orleans city and state leaders used dynamite to breach a levee at Caernarvon, thirteen miles (19 km) below Canal Street, to save the city of New Orleans from flooding. At the time, it was thought by New Orleans residents that the dynamiting saved the city, but historians now believe that the dynamiting was unnecessary due to major upstream levee breaks that relieved pressure on the New Orleans levees. The levee breach caused flooding and widespread destruction in most of Eastern St. Bernard Parish and parts of Plaquemines Parish. Residents were never adequately compensated for their losses.

On August 29, 2005, St. Bernard was devastated by Hurricane Katrina. The storm damaged virtually every structure in the parish. The eye of Katrina passed over the eastern portion of the parish, pushing a 25-foot (7.6 m) storm surge into the Mississippi River Gulf Outlet ("MRGO"). This surge destroyed the parish levees. Almost the entire parish was flooded, with most areas left with between 5 and 12 feet (3.7 m) of standing water. The water rose suddenly and violently, during a period which witnesses reported as no more than fifteen minutes. In many areas, houses were smashed or washed off their foundations by a storm surge higher than the roofs.

As of late November 2005, it was estimated that the Parish had some 7,000 full-time residents, with some 20,000 commuting to spend the day working, cleaning up, or salvaging in the parish and spending their nights elsewhere. By mid-December some businesses had returned to the Parish, most notably the ExxonMobil plant in Chalmette and the Domino Sugar plant in Arabi, together with a handful of small local stores and businesses. By October 2006, the population was estimated to be 25,489. After population losses due to Hurricane Katrina, the school was reopened for elementary grades for the 2006-2007 school year.

The parish has a total area of 1,794 square miles, of which 465 square miles is land and 1,329 square miles (74.07%) is water. The population recorded in the 1900 Federal Census was 5,031. The 2010 census recorded 35,897 residents in the Parish.

Neigboring parishes and counties are Hancock County, MS (east), Harrison County, MS (east), Plaquemines Parish (south), and Orleans Parish (west and northwes). Communities in the parish include Arabi, Chalmette, Versailles, Meraux, Violet, Caernarvon, Contreras, Delacroix Island, Hopedale, Kenilworth, Poydras, Reggio, St.Bernard Village, Shell Beach, Toca, Verret, Yscloskey, Fazendeville, Proctorville, and St. Malo

Birth Records - The Louisiana State office maintains records for 100 years after the date of birth. Birth records are considered confidential for the first 100 years. For current information on who may obtain a birth record as well as how to submit a request visit the Office of Public Health, Vital Records Registry website or write to them at PO Box 60630, New Orleans, LA 70160.

Birth records older than 100 years are available through the Louisiana State Archives, 3851 Essen Lane, Baton Rouge, LA 70809. (225) 922-1000.

Death Records - The Louisiana State office maintains records for 100 years after the date of death. Death records are considered confidential for the first 100 years. For current information on who may obtain a death record as well as how to submit a request visit the Office of Public Health, Vital Records Registry website or write to them at PO Box 60630, New Orleans, LA 70160.

Death records older than 100 years are available through the Louisiana State Archives, 3851 Essen Lane, Baton Rouge, LA 70809. (225) 922-1000.

Marriage Records - For current information on how to submit a request for a certified copy of an Orleans Parish marriage record less than 50 years old, see the Louisiana Office of Public Health Director, Vital Records and Statistics website or write to PO Box 60630, New Orleans, LA 70160.

Certified copies for the parish are issued by Clerk of Court. For the address of the parish Clerk of Court visit the St. Bernard Parish Important Addresses page.

Marriage records over 50 years are stored by the Louisiana State Archives, 3851 Essen Lane, Baton Rouge, LA 70809. (225) 922-1000.

Divorce Records - To obtain current information on how to submit a request for a certified copy of divorce records contact the Clerk of Court. For the address of the parish Clerk of Court visit the St. Bernard Parish Important Addresses page.