Dédé's instruction from Gabici ended when he left to seek work in Mexico at the end of the U.S.-Mexican War in 1848. When he eventually returned to the US at the end of 1852, he worked as a cigar maker, saving money to be able to travel to Europe. He went first to Paris and then Belgium, where he helped his friend Joseph Tinchant set up a branch of the Tinchant family's cigar Business. He returned to Paris around 1857 and became an auditeur at the Paris Conservatoire. He studied at the Conservatoire with Jean Delphin Alard and Fromental Halevy.
In the early 1860s, Edmond Dédé went to Bordeaux to take up a position as assistant Conductor for the ballet at the Grand Théâtre. Within a few years, he found employment at the Théâtre l'Alcazar, a popular café-concert in the city. Later in the 1870s, he moved to the Folies Bordelaises. Throughout Dédé continued to compose art music, which he sought to have performed at the more prestigious Grand Théâtre.
After settling in Bordeaux in 1864, he returned to New Orleans only once, in 1893. During the voyage to the United States, his freighter sank, occasioning a rescue. When he reached New Orleans, three benefit concerts were held in his honor, in which he participated. New Orleans' musical innovators and musical elite, including Jelly Roll Morton's Teacher, william J. Nickerson, took part in the concerts. The welcome committee that organized the concerts for Dédé overlapped with the membership of the Citizens Committee, the group of social and legal Activists who brought the legal challenges that led to the Plessy v. Ferguson ruling in 1896.
Samuel Snaer, Jr. (1835–1900), an African-American Conductor and musician, conducted the first performance in New Orleans of Dédé's Quasimodo Symphony. It was premiered on the night of May 10, 1865, in the New Orleans Theater to a large audience of prominent free people of color of New Orleans and Northern whites. Dédé was not present at this performance.
Dédé died on January 5, 1901 in Paris. Many of his compositions have been preserved at the Bibliothèque Nationale de France  in Paris.