Ruiz is known for writing The Resurrection of Fulgencio Ramirez and Valley of Shadows, magical realism novels which received critical acclaim and literary awards.

[1][2] In 2014, Ruiz authored Seven for the Revolution, a book that explores the "hard lives of Latinos and the fraught relations between their native and adoptive countries.

[4] Following the release of Ruiz’s novel, The Border Between Us, he was longlisted for the 2025 Joyce Carol Oates Prize, awarded to an “author of national consequence.

Ruiz also wrote an essay covering stereotypes and eating disorders called "Ghost of Gordolfo Gelatino," which was published in the book Going Hungry.

Reviewed as "vivid" and "palpable," the magical realism satire was highly critical of President Trump's border and immigration policies.

[27] In 2021, Ruiz’s short story, “Allegiance,” received Honorable Mention for the Dillydoun Review’s International Fiction Prize.

[29] Valley of Shadows was selected as the winner of the 2023 Texas Institute of Letters' Jesse H. Jones Award for Best Book of Fiction.

[7][5][6] As an advocate, Ruiz has regularly contributed to CNN on issues such as comprehensive immigration reform, and tighter regulation and taxes on sugary drinks and unhealthy foods.

[33][34] He served on the board of directors of Center for Science in the Public Interest, a leading non-profit nutrition advocacy group based in Washington, D.C.[35] He was also the founding editor of RedBrownandBlue.com, a multicultural political commentary website.