Bishop Leo was born on 1 December 1969 to Wilfredo Dalmao and Rosario Magdugo in Tagbilaran City, Bohol, Philippines. He was baptized at the St. Joseph Cathedral, Tagbilaran City, Bohol. He entered the Congregation in 1986 and studied AB Philosophy at Claret Formation Center now known as St. Anthony Mary Claret College. He made his First Profession on 3 May 1992 in Bungiao, Zamboanga City. He studied Bachelor in Sacred Theology and Masters at the Loyola School of Theology, Ateneo de Manila University in Quezon City from 1992 to 1997. He Perpetually Professed on 16 July 1996 in Quezon City and was ordained Priest by Msgr. José María Querejeta Mendizábal, CMF, Bishop of Isabela Prelature on 31 May 1997 at the Immaculate Heart of Mary Parish church in Quezon City. His first assignment after ordination was in the island of Basilan. He served as Project Coordinator for indigenous people Samal-Badjau. His years of stay in the place provided him a chance to know and experience the life and mission of the Claretians in the whole southern Philippines.
From Basilan he was appointed Prefect of Students in 2000 and three years later, became Novice Master while serving as Consultor and Prefect of Formation of the Philippine Province. He was elected Provincial Superior of the said Province in 2010. While serving as Superior, he also served as co-chairperson of the Association of Major Religious Superiors in the Philippines (AMRSP) until his election in 2015 as General Consultor and General Prefect of Formation of the Congregation during the XXV General Chapter held in Rome.
Pope Francis’ appointed Rev. Leo M. Dalmao on 25 Mar 2019, as Prelate of Isabela.
Romulo Tolentino de la Cruz (an. 28, 1989 Succeeded - Jan. 8, 2001 -now bishop of Kidapawan)