Santiago Roncagliolo spent most of his childhood in the city of Arequipa. His father, Rafael Roncagliolo, a renowned political analyst, was forced to temporarily leave the country with his family due to political tensions with the 1968 military government led by Juan Velasco Alvarado. The family resettled in Peru and Santiago continued his studies in Colegio de la Inmaculada. His writing career started with a few children's books and a short play called "Your friends would never harm you" (Tus amigos nunca te harían daño"). In 2000 he moved to Barcelona, Spain, where he continues to reside. He has commented that during the first few years of his stay in Barcelona he was forced to clean houses in order to pay his rent.
He is also a soap opera scriptwriter, an investigative journalist,a political analyst and a contributor for El País and other various Latin American newspapers.
He has been known for writing articles under different pen names.
His novel Abril Rojo ("Red April") won the Premio Alfaguara in 2006  and the Independent Foreign Fiction Prize in 2011. The novel's plot explores the vicissitudes of a diligent public prosecutor. It borrows heavily from Alan Moore's "From Hell".