Prolific writer, between 1900 and 1903 he collaborated under various pen names with some prominent publications of the time as O Paiz, O Dia (not the same newspaper of today), Correio Mercantil, O Tagarela and O Coió.

It was in this periodical that his most famous pseudonym was born, João do Rio, when on November 26, 1903 he signed an article called O Brasil Lê (Brazil Reads), an inquiry about the literary preferences of the Carioca reader.

Scholars had pointed out similarities between "As religiões no Rio" and the book "Les petites réligions de Paris" (1898), by French writer Jules Bois.

Some biographers criticize Barreto for the fact that, when he realised the bonanza he could obtain by the publication of collections (something that would become common in Brazil in the second half of 20th century), he developed a "formula" to inflate his own bibliography.

Elected for the Brazilian Academy of Letters in his third attempt (1910), Paulo Barreto was the first person to be admitted there wearing the now famous "fardão dos imortais" (the "robe of the immortals").

According to some biographers, when informed of his death, his mother ordered that the funeral service should not be held at the Academy hall, as usual for members, because her son would not have approved the idea.

However, for aspiring to defend new ideas in social and political fields, his "voluminous, thick-lipped and dark figure with a very smooth coat" (as registered by Gilberto Amado) became a perfect target for all sorts of reactionaries, homophobics and racists like Humberto de Campos.

Rodrigues (1996) talks about a factoid or hype, an expedient to attract the attention of the press, whilst other sources cite a supposed dialogue where the dancer would have questioned Barreto about his pederasty, and he would have answered in French: Je suis très corrompu (I am very corrupted).

In 1920, Barreto established the periodical A Pátria (The Fatherland, ironically called A Mátria–or The Motherland– by his detractors), in which he sought to defend the interests of the Poveiros, Portuguese fishermen from Póvoa do Varzim that supplied with fishes the city of Rio de Janeiro.

The activity of Barreto in favor of the Portuguese colony brought to him a lot of enemies, numberless moral offences (leaf lard with two eyes was one of the lightest) and even a despicable episode of physical aggression: entrapped alone when he took a meal in a restaurant, he was beaten by a group of nationalists.