As a musician, he composed about 80 works, including several operas, among them Aurora (1811-12), after Franz von Holbein, and Undine (1814), after Baron Friedrich de la Motte Fouqué's tale, one symphony, sacred and chamber music, as well as instrumental pieces.
His tales inspired many other authors (Edgar Allan Poe, Nikolai Gogol, Charles Dickens, Franz Kafka, Charles Baudelaire, among others) and also composers.
His most familiar story is “Nussknacker und Mausekönig [‘Nutcracker and Mouse King’]” (1816), which inspired Pyotr Ilyich Tchaikovsky's ballet The Nutcracker (1892).
Jacques Offenbach's masterwork, the opera Les contes d'Hoffmann [‘The Tales of Hoffmann’] (1881), is based on the stories “Der Sandmann [‘The Sandman’]” (1816), “Rath Krespel [‘Councilor Krespel’]” (1818), and “Das verlorene Spiegelbild [‘The Lost Reflection’]” from “Die Abenteuer der Silvester-Nacht [‘The Adventures of New Year's Eve’]” (1814).
Robert Schumann composed his Kreisleriana (1837) in homage to Hoffmann's most famous character, the genius musician Kreisler.
As musical critic, he set new standards for writing about music, and was the first one to describe music as "the most Romantic of all the arts." Most important is his review of Beethoven's Symphony No. 5 in C minor, Op. 67 (1808).
Some of his most important works as author are:
- Fantasiestücke in Callots Manier [‘Fantasy Pieces in the Manner of Callot’ or ‘Fantasias in Callot's Style’], 1814
- Die Elixiere des Teufels [‘The Devil's Elixir’] (1815–1816)
- Nachtstücke [‘Night Pieces’ or ‘Nocturnes’] (1816–1817)
- Die Serapions-Brüder [‘The Serapion Brothers’] (1819–1821)
- Lebensansichten des Katers Murr nebst fragmentarischer Biographie des Kapellmeisters Johannes Kreisler in zufälligen Makulaturblättern [‘The Life and Opinions of Tomcat Murr with a Fragmentary Biography of the Music Director Johannes Kreisler in Accidentally Intermingled Pages’] (1819–1821, fragment).