Rosati studied at the Academy of Rome under several eminent artists, including the poet and architect Francesco Podesti and Dario Querci, a portrait and history painter from Messina. He also studied with the director of the Prado Museum, Luis Alvarez y Catala, in Madrid.

Rosati was one of a large group of Italian Orientalist painters working in Rome at the end of the nineteenth century. Rosati was very skilful in his rendering of detail and bright coloring using rich intricate oriental patterns. He loved to paint the scenes from the camel markets, bazaars, and nude women in harems. This manner was particularly popular with American and British collectors, many of whom purchased these images as a memento of their travels in the Near East, a voyage very much in vogue at the end of the last century.

Giulio Rosati specialized in eighteenth century costume pieces, scenes of from the life of the clergy and Orientalist subjects. His preferred medium was watercolor, but he also worked in oils. He painted until one year before his death in 1917.