From the Sayago neighborhood, his childhood and youth house was in Calaguala street; and he grew up reading comics and being an avid supporter of his favorite soccer team, Club Nacional de Football.

The editor for the newspaper's children's magazine (El Día de los Niños) liked Barreto's art, but he asked him to do something more Hispanic.

In 1974 he created a science fiction and space opera strip inspired by The Morning of the Magicians, a book by Louis Pauwels and Jacques Bergier.

The publisher's chief art editor, Antonio Presa, asked him why he hadn't answered the letter in which they offered him a position working on the strip Kabul de Bengala.

Eventually, tired of Ray Collins' (Eugenio Zapietro) scripts, he signed his Kabul art with aliases, such as "S. Gneis" or "Kopy"; using the latter when he had to copy another artists' styles.

In 1989 he illustrated the prestige format graphic novel Lex Luthor: The Unauthorized Biography, written by James D. Hudnall, in which Superman is practically absent, instead featuring Clark Kent in his investigative journalist role.

[9][10] In the 1990s Barreto worked with several companies and characters, such as Dark Horse Comics, for whom he drew Indiana Jones, Aliens/Predator: Deadliest of the Species, and Star Wars: A New Hope – The Special Edition.

[9] For DC Comics, his 1990s work included Superman: Speeding Bullets,[11] Justice League Quarterly, Sgt.

For Tekno Comics he drew Mickey Spillane's Mike Danger, about a hard-boiled detective who finds himself in a futurist world.

He would also work for IDW Publishing on Cobb: Off the Leash and Doomed, and for Moonstone Books' Captain Action the latter two written by Beau Smith.

Studios' Planetary Brigade, and the following year he did a short story for Marvel's Civil War: Front Line.

Shortly afterwards, Barreto suffered a serious car accident, and while he was in the hospital, Judge Parker's art was undertaken by artists such as Graham Nolan, John Heebing, and Eduardo Barreto's son Diego, who had been working as an artist for a few years already, mainly in advertising but doing some work for U.S. comic publishers.

Among the things he worked on in his country were comic stories for the book Historiet@s.uy (2000) and Freeway magazine; and the cover for Jaime Roos's album "Hermano Te Estoy Hablando" (2009).

Barreto eventually returned to Judge Parker, and continued working on that and occasional stories with other characters, such as Superman and Captain Action.

In April 2011 it was announced that Eduardo Barreto and his son Diego would work on Irredeemable, and in July 2011 he took over the art for The Phantom's Sunday strips.

His last published work was in DC Retroactive: Superman - The '70s (Sept. 2011), finished from his hospital bed, and with some pages drawn by fellow Uruguayan Christian Duce.