Marc Haydel Morial was the second child born in New Orleans to Ernest N. (Dutch) Morial and Sybil Haydel Morial. Morial grew up in the Pontchartrain Park subdivision of New Orleans and attended Jesuit High School. After graduating, he attended the University of Pennsylvania in Philadelphia before getting his law degree from Georgetown University.

Morial served as a lawyer before getting elected to the State Senate in 1991. As a lawyer, he argued as a plantiff in the case Chisom v. Roemer, which established that the Voting Rights Act of 1965 covered judicial elections. After being elected to the State Senate, Morial served as a member of the Louisiana Legislative Black Caucus and as chairman of the Education Institution Subcommittee.

In 1994, Morial became the youngest person elected Mayor in New Orleans history, defeating Donald Mintz with 54% of the vote. He was reelected in 1998 and completed his two terms in office in 2002. Morial inherited a city that continued to be plagued with many of the problems his father dealt with in the late 1970s and early 1980s. The Justice Department released a report on police brutality in 1992 finding that the New Orleans Police Department was among the most violent in the nation. New Orleans also had an extremely high murder rate, counting over 400 murders in 1994 alone. Parks and playgrounds were derelict and many residences and busineses had been abandoned to blight and crime. Furthermore, disputes between the state, federal, and municipal governments continued to hamstring the city's economic initiatives, including expanding the Morial Convention Center and updating the New Orleans International Airport.

During his time in office, Morial oversaw many reforms and pushed through new initiatives. He hired Richard Pennington as Chief of Police and both assisted the Justice Department investigate corrupt and violent police officers. While problems with the department remained, the number of officers hired by the department increased during this time and the overall crime rate sank. Morial's administration doubled the parks budget and began public/private partnerships to address housing issues, especially home ownership. He oversaw the passage of a large bond to help economic development and infrastructure, overseeing the revitalization of Canal Street and the expansion of the Convention Center. To bolster the city's tourism infrastructure, the mayor worked to facilitate the construction of a new sports arena as well as the construction of new museums in the city's warehouse district and central city. These includes the D-Day Museum, the Ogden Museum of Southern Art, and the Ashe Cultural Center.

During his tenure as mayor, he served as the President of the United States Conference of Mayors, Chairman of the Committee on Arts, Chairman of the Federal Budget Task Force, and the Chairman for the Task Force on Hunger and Homelesseness. After leaving office in 2002, Morial became the head of the National Urban League in 2003.