Washington Parish is a parish located in the interior southeast corner of the U.S. state of Louisiana, one of the Florida Parishes. As of the 2020 census, the population was 45,463. Its parish seat is Franklinton. Its largest city is Bogalusa. The parish was founded in 1819.

The Florida Parishes, on the east side of the Mississippi River—an area also known as the Northshore or Northlake region—are eight parishes in the southeastern portion of the U.S. state of Louisiana.