Carlos Velero Mendoza was born in Santa Cruz de Juventino Rosas, Guanajuato, Mexico. He is the oldest of three children. Prior to the age of fifteen he had never thought about becoming a priest, until people started telling him if he had ever considered it. He had always seen himself as getting married and having a large family and rejected the idea at the time. However, his Confirmation at the age of eighteen began the turning point as a desire grew within him to serve the Church. Through volunteering at his home parish, St. Benedict the Abbot, and at the Office of Evangelization and Catechesis of the Archdiocese of Galveston-Houston, he saw the Lord calling him to serve the Church, though it was unclear to him in which capacity.
After attending the University of Houston for two and a half years, he began attending daily Mass and Adoration his last semester there to see what God was calling him to do in his life and slowly started to become open to discerning a vocation to the priesthood. As a result, he transferred to the University of St. Thomas to study Theology. After a year and a half, retreats, and spiritual guidance the call became clear and he applied to become a seminarian for the Archdiocese of Galveston-Houston. Upon being accepted he attended St. Joseph Abbey and Seminary College in Covington, Louisiana for three years. In the fall of 2020, he began his Theology seminary formation at St. Mary’s Seminary in Houston, Texas. On February 14, 2021, he received the institution of the Ministry of Lector from Bishop Joe Vasquez of the Diocese of Austin, Texas and on November 14, 2021 he received the institution of the Ministry of Acolyte from Bishop Italo Dell’Oro, auxiliary bishop of the Archdiocese of Galveston-Houston.