Lunel was born in Aix-en-Provence, France, to a family that belonged to a Jewish subculture that had roots in the area for at least five centuries. After coming of age in the region, Lunel taught law and philosophy in Monaco. Lunel wrote extensively about the Jews of Provence.
He was a childhood friend of the composer Darius Milhaud, and wrote the librettos of Milhaud's operas Esther de Carpentras ("Esther of Carpentras," 1938, based on Shuadit folklore) and Les malheurs d'Orphée ("The Misfortunes of Orpheus," 1924). He also provided the libretto for Henri Sauguet's La chartreuse de Parme, premiered in 1939.
He married Rachel Suzanne Messiah, a daughter of architect Aron Messiah in 1920.
Most of the current knowledge about Lunel was collected by his son-in-law: Georges Jessula.