Born in Italy at Velletri, 30 km south-east of Rome, Leroux was the son of a French military bandleader.
Notable students include Eugène Bigot, Georges Dandelot, Marc Delmas, Roger Désormière, Louis Fourestier, Henri Mulet, Paul Paray, Louis Vuillemin, and Albert Wolff.
Leroux composed various orchestral and choral works, songs, and piano pieces, but he became known above all as a representative of naturalistic French opera.
It was revived at the Marseille Opera in January 1996, featuring Jean-Philippe Lafont and Martine Surais, directed by Henri Gallois.
Leroux was married to the Brussels-born soprano Marie-Antoinette Willemsen, who appeared under the pseudonym Meyrianne Héglon (1867–1942).