One of seven children, Josu Iriondo was born on December 19, 1938, in Legazpi, Spain, to Rufino and Maria Leona (née Zabaleta) Iriondo.[1] He was educated in Spanish, but spoke Basque at home.[1]
Iriondo was ordained into the priesthood by Bishop Jaime Font y Andreu for the Canons Regular order in San Sebastián, Spain, on December 23, 1962.[2][3] He then served as professor and master of discipline at a Canons Regular seminary and traveled through Europe on duties related to his religious order.[1] Iriondo also taught at the National Institute, a regional public high school, where served as school secretary as well.[1]
Iriondo was named parochial vicar (1976) and then pastor (1978) of Our Saviour Parish in the Bronx, New York.[1] In 1990, he was appointed director of both the Hispanic Catholic Center and the Charismatic Renewal Movement.[4] Iriondo was incardinated, or transferred, from the Canons Regular Order into the Archdiocese of New York on December 4, 1996, and named vicar for Hispanics in 1997. Iriondo became pastor of St. Anthony of Padua Parish in 2001.[2]