Hasse began his career as a singer and made his debut as a composer in 1721 with the opera Antioco. He went to Italy, where he studied with Nicola Porpora and with Alessandro Scarlatti and where his opera seria Sesostrate (1726) established his reputation; in Italy he became known as “il Sassone” (“the Saxon”). After spending several years in Venice, where he married the celebrated mezzo-soprano Faustina Bordoni (c. 1700–81), he became music director of the Dresden Opera (1731). He resided in Dresden from 1739 to 1763, when he retired and went to Vienna. His last work for the stage was Ruggiero (1771), written for the wedding of the archduke Ferdinand at Milan.

Hasse's compositions include more than 60 operas, many of them to librettos by Pietro Metastasio, and nearly a dozen intermezzos, as well as oratorios, masses, and instrumental works. His music was enormously popular during his lifetime; its chief characteristics were melodic beauty and formal balance. His operatic overtures had considerable influence on the development of the symphony, especially in northern Germany.