He was born in Caleruega, a mountain village in Old Castile, into a noble family. Son of Felix of Guzmán and Giovanna of Aza, from an early age he was entrusted to an uncle who was a priest to take care of his education. Almost naturally, Domenico's life was oriented towards a priestly vocation.

He began his studies at the University of Palencia. It was during a time of famine, that yes realizes that studying or preaching the Word of God means, first and foremost, embodyìng it. For this reason he sold his books to give charity to the poor.
At the conclusion of his studies, he was invited by the prior of the Chapter of Osma - Diego de Acebés - to join the Canons Regular of the Cathedral where at the age of 24 he was ordained a priest.

Dominic was invited by Diego of Acebés, who had become bishop, to a diplomatic mission in Denmark; while traveling through southern France they came into contact with the populations under the influence of the Cathar heresy and his awakened in their hearts the desire to become missionaries among those who had strayed from the faith.
In 1206 Dominic founded a women’s community in Prouille gathering those women who had abandoned heresy. Through prayer and service, they were to support the work of preaching.
In this same year, at the conclusion of a second mission to Denmark, Dominic and Diego asked Pope Innocent III for permission to dedicate them fully to preaching to pagans.

They returned to France and shortly after, Diego died. At first Dominic continued the preaching against heresy alone, with passion, meeting people, exhorting them and proclaiming the Gospel.
Some companions gradually joined his mission and within Dominic grew the desire to give preaching a stable and organized form.
In 1215 he participated in the Fourth Lateran Council and submitted to Pope Honorius III the project of founding an Order of friars totally dedicated to preaching; on 22 December 1216 the «Order of Friars Preachers» was officially approved.

El 15 de agosto de 1217, Domingo extendió a sus frailes por Europa, especialmente en los principales centros universitarios de la época; hace todo lo posible para difundir la Orden.
Preside los dos primeros Capítulos Generales, donde se delinean los elementos fundamentales de la Orden: los frailes son enviados a las fronteras, fundados en la Palabra y caracterizados por la búsqueda de la Verdad encarnada en una fraternidad cada vez más universal.

Consumed by his passionate desire to serve God by giving life to the world, Domenico died in Bologna.

Pope Gregory IX proclaimed him a saint.