Walter Guillen Soto was born on 6 December 1961 in San Pedro Sula, Honduras. He holds: a Licentiate in Theology from the "Universidad Francisco Marroquín" in Guatemala; in Pedagogy and Educational Sciences at the "Universidad Don Bosco" in San Salvador, El Salvador; and a Doctorate in Education and Pedagogical Sciences from the "Universidade de Santiago de Compostela", Spain.
He made his religious profession as a Salesian of Don Bosco on 6 June 1986 and received priestly ordination on 5 November 1988.
In his religious life he has held the following positions: Academic Director of the "San Miguel" Institute in Tegucigalpa; Director of the Archdiocesan Theological Institute of Tegucigalpa; Director of the "Ricaldone" Institute in San Salvador; Director of the Don Bosco College of San José, Costa Rica; Director of the "Instituto Técnico Don Bosco" in Panama City, Panama; Director of the "Instituto Tecnológico Don Bosco AC" in Saltillo, Mexico; personal secretary of the Archbishop of Tegucigalpa, Salesian card. Óscar Andrés Rodríguez Maradiaga.
Since 2017 he has been Rector of the "San Juan Bosco" Shrine of Tegucigalpa and since 2018 Chaplain General of the Catholic University of Honduras. He was also President of the Catholic Federation of Panama and President of the Inter-American Confederation of Catholic Education (CIEC).
Together with Fr Guillen Soto, the Holy Father also appointed Fr Teodoro Gómez Rivera, of the clergy of the diocese of Choluteca Honduras, currently Vicar General and Episcopal Vicar for the pastoral care of the diocese, as auxiliary bishop of Tegicigalpa, and assigned him the titular see of Tatroporto Castle.