Hieronymus Praetorius wrote masses, ten settings of the Magnificat, and numerous motets, mostly in Latin. Most of his music is in the Venetian polychoral style, which uses numerous voices divided into several groups. These compositions are the first to be written in north Germany in the progressive Venetian style. Choir sizes range from 8 to 20, with the voices divided into two, three or four groups, and he must have had well-trained and sophisticated musicians at his disposal, considering both the amount and the difficulty of music he wrote for these ensembles.
While progressive in writing in the Venetian style, he was conservative in using Latin and avoiding the basso continuo, which was eagerly adopted by many other contemporary German composers. Most of his vocal music is a cappella.
Praetorius was also the first composer to compile a collection of four-part German chorales with organ accompaniment, a sound which was to become a standard in Protestant churches for several centuries. The music in the collection was compiled from four churches in Hamburg; 21 of the 88 settings are of his own composition.
Some of his organ compositions survive, including nine settings of the Magnificat, which are in a highly contrapuntal cantus firmus style. In addition to these settings, numerous anonymous pieces in north German collections of the time are now attributed with reasonable certainty to Hieronymus Praetorius.