He is considered the founder of the avant-garde in Peru, although more for his dandy-like public poses and his founding of the journal Colónida than for his own writing, which is lyrically posmodernista rather than aggressively experimental.
Like Charles Baudelaire in 19th century Paris, he claimed to have made his country aware for the first time of the relationship between poetry and the market, and to have recognized the need for the writer to turn himself into a celebrity.
However, in 1906 he began contributing caricatures and poems to a number of illustrated magazines and periodicals, such as Aplausos y silbidos, Monos y Monadas, Actualidades, Cinema and Gil Blas, and he soon abandoned university life completely for the world of journalism.
Valdelomar promised to provide a prologue for Vallejo's first collection of poetry, Los heraldos negros, but his ambitious lecture tours of the provinces distracted his attention.
He was also the author of two important essays: the first, "La sicología del gallinazo," an anti-tourist, unembellished guide to Lima and its psychology, which would later influence Julio Ramón Ribeyro; the second, "Belmonte el tragico," a study of bullfighting.