Born in Meurthe-et-Moselle, Schmitt took music lessons in Nancy with the local composer Gustave Sandré. At the age of 19 he entered the Paris Conservatoire, where he studied with Gabriel Fauré, Jules Massenet, Théodore Dubois, and Albert Lavignac. In 1900 he won the Prix de Rome. During the 1890s he became friendly with Frederick Delius, who was living in Paris at the time, and Schmitt prepared vocal scores for four of Delius's operas: Irmelin, The Magic Fountain, Koanga and A Village Romeo and Juliet.
From 1929 to 1939 Schmitt worked as a music critic for Le Temps, where he proved controversial. He was known to shout out his views from his seat in the hall. The music publisher Heugel called him "an irresponsible lunatic". In November 1933, at a concert that included music by Kurt Weill, who had just been forced to leave Germany and was present, Schmitt led a group in shouting "Vive Hitler!".
Schmitt wrote 138 works with opus numbers. He composed examples of most of the major forms of music, except for opera. His piano quintet in B minor, written in 1908, helped establish his reputation. Other works include a violin sonata (Sonate Libre), a late string quartet, a saxophone quartet, Dionysiaques for wind band, and two symphonies. He was part of the group known as Les Apaches. His own style, recognizably impressionistic, owed something to the example of Debussy, though it had distinct traces of Wagner and Richard Strauss also.
In 1907 Schmitt composed a ballet, La tragédie de Salomé, to a commission from Jacques Rouché for Loie Fuller and the Théâtre des Arts. The original ballet score required twenty instruments and lasted about an hour, In 1910 Schmitt prepared a suite using several of the ballet's movement, half as long as the ballet score, for a much expanded orchestra. The suite is much better-known, with recordings conducted by Schmitt himself, Paul Paray, Jean Martinon, Antonio de Almeida, Marek Janowski and others. There is also a recording of the 1907 original score under Patrick Davin on the Marco Polo label. The rhythmic syncopations, polyrhythms, percussively treated chords, bitonality, and scoring of Schmitt's work anticipate Stravinsky's The Rite of Spring. While composing The Rite of Spring, Stravinsky acknowledged that Schmitt's ballet gave him greater joy than any work he had heard in a long time, but the two composers fell out with each other in later years, and Stravinsky reversed his opinion of Schmitt's works.
Schmitt was one of the ten French composers who each, in 1927, contributed a dance for the children's ballet L'éventail de Jeanne. Schmitt wrote the finale, a Kermesse-Valse.
Other works include the suite for orchestra "Oriane et le Prince d'Amour" op. 83 bis (1934), the symphonic diptych to the memory of Gabriel Faure "In Memoriam" op. 72 (1937), the "Ronde Buelesque" op. 78 (1927), the "Legende pour alto et orchestre" op. 66 (1918), and the orchestral fresco "Anthony and Cleopatra" (1920).
Though he was one of the most often performed French composers during the first four decades of the 20th century, Schmitt fell into comparative neglect, though he never stopped composing. (In 1952 he was admitted to the Légion d'honneur.) He became the subject of attacks — both in his last years and posthumously — over his pro-German sympathies during the 1930s, and over his willingness to work for the Vichy regime in the 1940s, as had other eminent French musicians, notably Alfred Cortot and Joseph Canteloube.
He died in Neuilly-sur-Seine in 1958, aged 87.
The 1990s and 2000s witnessed a revival of his output, and an increased coverage of it on compact disc. Beginning in late 2012, the Invencia Piano Duo (Andrey Kasparov and Oksana Lutsyshyn), in collaboration with Naxos Records, on its Grand Piano series, released four CDs of Schmitt's complete duo-piano works. The collection includes Schmitt's Trois rapsodies, Op. 53, and the first recording of Schmitt's Sept pièces, Op. 15, composed in 1899. It also includes one of two unpublished duets by Schmitt, Rhapsodie parisienne (1900).3 symphonies :
Symphonie concertante, Op. 82 for orchestra and piano
Janiana symphony for strings
Antoine et Cléopâtre
Introït, récit et congé, Op. 113 for cello and orchestra (1949)
Kermesse-Valse from L'éventail de Jeanne (1926)
Le Palais Hanté [The Haunted Palace]
Le Petit Elfe Ferme-l'œil
Légende for alto saxophone (or viola, or violin) and orchestra
Salammbô (film music)
Salammbô (3 suites)
Pour presque tous les temps for flute and piano trio
Sonata for violin and piano
Trio sonatina for flute, clarinet and keyboard
Suite for Trumpet and piano, Op. 133
Le chant de nuit pour soloists, chorus and orchestra
Mass for four voices and organ
Psaume XLVII for soprano, chorus, organ and orchestra (1906)
La Tragédie de Salomé (1907)
Oriane et le prince d'amour
Reflets d'Allemagne, Op. 28 (1905)
Musiques foraines, Op. 22
Crépuscules, Op. 56
Ombres, Op. 64
Mirages, Op. 70