He studied medicine briefly, largely to satisfy his father's wishes, but gave it up for the life of a poet.

He even wrote a series of youthful stories à la E. T. A. Hoffmann and Edgar Allan Poe set in an imaginary German town inhabited by sinister students and mad doctors.

He was also an expert of the history of his land, and he published the work Per la storia del brigantaggio nel Napoletano in 1904.

Di Giacomo's plays, such as A San Francesco and Assunta Spina, are bitter stories about turn-of-the-century life in the Naples of the Risanamento (the massive, decades-long urban renewal of the city that displaced tens of thousands of persons), workers whose health is ruined by their labors, prostitution, betrayal, prison, crime, etc.

He closed his own essay on Neapolitan poetry, written in 1900, with this passionate quote from Dante: "With the gifts God gives us from Heaven, we shall try to renew the language of the common people."