New Orleans has a mayor-council government. The city council consists of five council members who are elected by district and two at-large councilmembers. Mayor Ray Nagin was elected in May 2002 and was reelected in the mayoral election of May 20, 2006.

The Orleans Parish Civil Sheriff's Office serves papers involving lawsuits and provides security for the Civil District Court and Juvenile Courts. The Criminal Sheriff, Marlin Gusman, maintains the parish prison system, provides security for the Criminal District Court, and provides backup for the New Orleans Police Department on an as-needed basis.

The city of New Orleans and the parish of Orleans operate as a merged city-parish government.[73] Before the city of New Orleans became co-extensive with Orleans Parish, Orleans Parish was home to numerous smaller communities. The original city of New Orleans was composed of what are now the 1st through 9th wards. The city of Lafayette (including the Garden District) was added in 1852 as the 10th and 11th wards. In 1870, Jefferson City, including Faubourg Bouligny and much of the Audubon and University areas, was annexed as the 12th, 13th, and 14th wards. Algiers, on the west bank of the Mississippi, was also annexed in 1870, becoming the 15th ward. Four years later, Orleans Parish became coextensive with the city of New Orleans when the city of Carrollton was annexed as the 16th and 17th wards.

New Orleans' government is now largely centralized in the city council and mayor's office, but it maintains a number of relics from earlier systems when various sections of the city ran much of their affairs separately. For example, New Orleans has seven elected tax assessors, each with their own staff, representing various districts of the city, rather than one centralized office. A constitutional amendment passed on November 7, 2006, will consolidate the seven assessors into one by 2010.