He was a member of a distinguished family of French musicians. Casadesus studied with Louis Diémer at the Paris Conservatory where he won several prizes, including the Grand Prix Diémer. Beginning in 1922, he toured extensively in Europe, South America, the United States, and Canada, making his U.S. debut under Arturo Toscanini in 1935. He taught at the American Conservatory at Fontainebleau and in the United States during World War II.

He recorded the complete piano music of Maurice Ravel. In addition to the works of French composers, Casadesus frequently performed music by Wolfgang Amadeus Mozart, Ludwig von Beethoven, and Robert Schumann. His playing was marked by extreme clarity and a Gallic sense of balance. A prolific composer, he wrote works considered adventurous but balanced.