It has been claimed that he was a student of Palestrina, but there is no documentary evidence of this; stylistic similarities between their music, and an obvious close career association, make it a reasonable assumption.
Not much is known about Giovannelli's life until 1583 when he became maestro di cappella at S Luigi dei Francesi, a post which he held until 1591, at which time he went to the Collegio Germanico.
[1] In addition to these posts he was maestro di cappella for Duke Giovanni Angelo of Altaemps, at his private chapel, probably concurrently with his other jobs.
[2] As could be expected for a composer of the Roman School, his sacred music was conservative, and mostly in the Palestrina style for the first part of his career; however, after 1600 he experimented with some of the stylistic innovations which defined the beginning of the Baroque era, such as the concertato principle and the basso continuo.
His output of sacred music fell off dramatically late in his life, and at least one scholar[3] has suggested that this was because he was uncomfortable with the new style.
For a Roman School composer and a priest he wrote a surprising amount of secular music, mostly madrigals and canzonettas, some of which are in a light-hearted style influenced by northern Italian models, or by Luca Marenzio, who had spent time in Rome.