Fr. Javier del Castillo was born in Mexico in 1975 and grew up in various cities in Mexico and the United States. He earned a degree in electronic engineering from Cooper Union (New York, 1998).

After graduating, he worked at Symbol Technologies in Long Island, New York. In 2000, he moved to Rome to complete his ecclesiastical studies, where he was ordained a priest in 2005 and earned a doctorate in Philosophy from the Pontifical University of the Holy Cross in 2007.

He worked as a chaplain in high schools in the Washington, D.C. and Chicago areas for several years, offering spiritual accompaniment to students, parents, and teachers. From 2015 on, he served as the vicar of Opus Dei in the midwest; he was appointed regional vicar of the United States in 2022. He became vicar of the United States and Canada in 2024, following the restructuring of the regions, until his appointment as Vicar General in April 2025.