Marcello was born on February 6, 1910 to Sicilian immigrants Giuseppe and Luigia Minacore, in Tunis, French Tunisia. With his family, Marcello immigrated to the United States in 1911 and settled in a decaying plantation house near Metairie in Jefferson Parish, a suburb of New Orleans. His father adopted a different family name to avoid confusion with his supervisor on the sugar plantation where he had started work. His overseer, also Minacore, chose the appellation Marcello. The family changed all their other names, and Calogero Minacore became Carlos Joseph Marcello. He had eight siblings: Peter, Rose, Mary, Pascal, Vincent, Joseph Jr., Anthony and Salvador Marcello.