Quiñonez was born in Ecuador and raised in East Harlem, New York. He was the youngest of five children and no stranger to hardship: his Puerto Rican mother was a seamstress in a garment district sweatshop, and his father worked in a factory until a steel drum fell on his back.

Quiñonez attended New York City public schools and received a Bachelor’s degree in English from the City University of New York. He then taught fourth grade English in the South Bronx, while writing his first novel.

Quiñonez’s first novel, Bodega Dreams, was published in 2000 and received immediate critical acclaim. The New York Times declared it “a New Immigrant Classic” and “a stark evocation of life in the projects of El Barrio...the story he tells has energy and nerve.” Time Magazine announced that “Quiñonez knows this 'hood--readers may have to remind themselves that this is a work of fiction and not a memoir. His prose, detailed and passionate, brings the tale to life.” The novel was chosen as a Barnes & Noble Discover Great New Writers title, as well as a Borders Bookstore Original New Voice selection. It was also named a “Best Book” by the New York Times and the Los Angeles Times.

Quiñonez’s second novel Chango’s Fire solidified his international reputation as a literary novelist, and a voice for a new generation of Latinos throughout the United States. The Washington Post declared that Chango’s Fire “succeeds in its rich characterizations of the people of the barrio, led by Julio, whose complexity and sensitivity carry the story.” The El Paso Times praised Quiñonez's “extraordinary ability to detail, and nurture, and then unveil complex emotions in his characters. For any reader who wants to believe in a difficult protagonist, and appreciate the reality of El Barrio beyond facile stereotypes, this book is essential.” Kirkus Reviews hailed “Quiñonez's ingeniously detailed revelations of how people cheat and improvise, to survive in an impoverished and dangerous racist environment. This is an author who knows his material.” Booklist heralded it as a “searing portrait of a community at the tipping point...Quiñonez ably illuminates the sordid politics of gentrification and the unexpected places new immigrants turn to for social and spiritual support.”

Quiñonez has written for the New York Times and received fellowships from the Wesleyan Writer's Conference, the Breadloaf Writer’s Conference and the University of Indiana. In 2003 he was chosen as a visiting screenwriter at the Sundance Screenwriter Lab in Provo, UT.Quiñonez is currently a member of the graduate faculty at the Cornell University M.F.A. creative writing program. He is working on his next novel Taina’s Song, and the short story collection Botanica Tales.