Sylvia, and Coppélia before it, are often touted as two of the first modern ballets for their novel scores. Tchaikovsky himself remarked to fellow composer Sergei Taneyev upon the ingenuity of Sylvia, calling it "... the first ballet, where the music constitutes not only the main, but the only interest. What charm, what elegance, what richness of melody, rhythm, harmony." While this statement may be a little hyperbolic, it says something very important about the uniqueness of the ballet. Sylvia's score is varied and rich, and it stands out, drawing the focus from the sets, the dancers, the costumes. Instead of receding into the background, setting only the mood, Delibes' score sets the action. The music of Sylvia was also notable for its new, more developed use of leitmotifs. Such a stylistic choice is characteristic of Delibes, who was a great admirer of Wagner. Indeed, echoes of Wagner's influence are quite obvious in the music such as its "symphonic" nature, as described by Ivor Forbes Guest in the 1954 edition of The Ballet Annual.

Another interesting choice of Delibes was his pronounced use of brass and wind instruments, especially in the characteristically powerful prelude. Delibes was also one of the first composers to write for the alto saxophone, an instrument used extensively in the heavier wind sections such as the barcarolle in Act III.

The prelude to the first act and the pizzicati in the third are the significantly more famous sections of this already notable score. The latter, the more famous, is a well-known example of pizzicato style. This section is, according to The New Grove Dictionary of Music and Musicians, "traditionally played in a halting, hesitant style that appears to have been no part of Delibes's conception."