After his execution, Benito de Soto's legacy in Spain only grew. He is often believed to be the inspiration for the romantic poet Jose de Espronceda's 1835 celebrated poem La Cancion del Pirata (The Pirate's Song), although there is no evidence to support this assertion. The poem is known to have inspired a series of other widely distributed poems. The Defensor de Pedro story appeared in Alejandro Benisia's 1855 novel El Milano de los Mares (The Kite of the Seas), although it positions Barbazan as the hero of the story, not de Soto. By the twentieth century, the publication of Philip Gosse's History of Piracy in Spanish introduced the Black Joke (known in Spanish as La Burla Negra) myth into the narrative around Benito de Soto. The story was solidified in Spanish folklore in 1955, when novelist Jose Maria Castroviejo titled his version of the Benito de Soto story La Burla Negra. The sanitisation of his murderous piracy into the actions of a folk hero was further memorialised when the local councils of Pontevedra and Cadiz named streets after him.

The so-called discovery of some of Benito de Soto's treasure also fed into his legacy. In 1926, contractors excavating the foundations of a new house in the village of Mouriera, apparently near Benito de Soto's family home, uncovered a thick iron trunk. There was no mention of what, if anything, was inside it. The article also goes on to falsely describe how de Soto's next adventure after abandoning the trunk in Pontevedra was ‘a fight with some Sallee pirates off Mogador’, so its accuracy is rather questionable. However, the local Pontevedra newspaper, El Diario de Pontevedra, confirmed the story. The discovery of the mysterious chest was the talk of the town. A great crowd assembled at the construction site to try and gain a glimpse of it. Yet nobody seemed to know what was inside it. An elderly gypsy lady called Manuela Rodina told the local reporter that she had lived in the house being excavated for many years and it had been previously occupied by members of Benito de Soto's family. A well-known elderly sailor even went to the police to unsuccessfully lay claim to the chest because his wife was a descendant of Benito de Soto's mother.