On June 29, 1935, Father Dominic Mary Hồ Ngọc Cẩn was ordained as a Bishop in the Catholic Church at Phủ Cam Main Cathedral. His Coat-of-arms bore the motto: “In Omni Patientia et Doctrina” which means “In everything Patience and Teaching.” He was the second Vietnamese priest to be  named of Bishop following the Bishop Jean-Baptiste Nguyễn Bá Tòng. After one year as Deputy Bishop, Bishop Dominic Mary Hồ Ngọc Cẩn succeeded Bishop Pedro Munagorri Trung as the Diocesan Bishop of Bui Chu.