Ruben Caballero Labajo was born on September 24, 1966, in Poblacion, Talisay City, Cebu, Philippines, to Bienvenido and Violeta Labajo. He undertook his priestly formation at San Carlos Seminary College in Cebu City, obtaining a degree in philosophy, followed by theological studies at the Seminario Mayor de San Carlos, earning a master’s degree in theology.
Labajo was ordained a priest on June 10, 1994, at Our Lady of Guadalupe Parish in Talisay by Archbishop Ricardo Cardinal Vidal. His early assignments included serving as Parochial Vicar in Mandaue City (1995–1997) and then as Parish Priest of Santa Fe Parish on Bantayan Island (1997–2006).
From 2007 to 2014, he was Team Moderator at St. Joseph the Worker Parish in Tabunok, Talisay, and subsequently served as Moderator of the pastoral team at the Cebu Metropolitan Cathedral (2014–2017). During that period, he also became Vicar Forane of the Vicariate of the Most Holy Rosary (2014–2019). Starting in 2017, he joined the diocesan College of Consultors and the Presbyteral Council, while also being appointed Episcopal Vicar for the First District of Cebu.
By 2020, he was elevated to Vicar General of the Archdiocese of Cebu, concurrently serving as senior chaplain at St. Francis of Assisi Parish in Balamban.
On June 23, 2022, Pope Francis appointed Labajo as Auxiliary Bishop of Cebu and titular bishop of Abbir Maius. He was consecrated on August 19, 2022, by Archbishop Jose Palma, with Papal Nuncio Archbishop Charles John Brown and Bishop Dennis Villarojo as co‑consecrators.
Shortly after his consecration, he was assigned as Team Moderator at Sto. Rosario Parish in Cebu City, a move intended to make him more accessible to the faithful in Metro Cebu.
On October 15, 2024, Pope Francis erected the Diocese of Prosperidad in Agusan del Sur—Philippines’ 87th diocese—and installed Ruben Labajo as its first diocesan bishop. Labajo’s installation took place on January 28, 2025, at St. Michael the Archangel Cathedral in Prosperidad, with Archbishop Jose Cabantan presiding and Papal Nuncio Charles John Brown among the dignitaries present. During the installation Mass, Labajo emphasized his commitment to accompany the faithful of Agusan del Sur as a “fellow pilgrim” in their synodal journey toward growth in faith, hope, and charity. The ceremony drew approximately 40 bishops, 200 priests, family members, clergy from Cebu who traveled by boat, and local officials from Agusan del Sur.