As a priest, Father Mark Garrett served two years as parochial vicar of St. Monica Catholic Church and School. After his first year there, he was also assigned as chaplain of Bishop Lynch High School. In July of 2022, Father Garrett left St. Monica and was assigned to the National Shrine Cathedral of Our Lady of Guadalupe, while maintaining his role as chaplain at Bishop Lynch. Father Garrett then moved to the Diocese of Dallas Office of Vocations and began working as vocations director for the diocese on July 1, 2023. He has been serving as vocation director ever since and as chaplain of Bishop Lynch High School since July of 2021.