Jalandoni hails from a wealthy family in Silay, Negros Occidental.[1] He would become a Roman Catholic priest in Negros. He also donated farmlands he inherited from his family in the 1960s to landless workers.[2]
In 1972, Jalandoni was involved in the establishment of Christians for National Liberation. The NDFP credits Jalandoni for his role of involving Catholic and Protestant faithful to the Communist movement. He was arrested by the authorities in the following year with nun Coni Ledesma.[2] They were released in mid-1974.[3]
He went to exile in the Netherlands. He became a close aide of Communist leader Jose Maria Sison.[4]
From 1989 to 2016, Jalandoni served as the chief peace negotiator for the Communist rebels in negotiations with the Philippine national government.[2]
Jalandoni is married to Maria Consuelo "Coni" Ledesma, a former nun and school principal.[1] Jalandoni was released from priesthood in 1974 and Ledesma received her dispensation in December 1972. The two formally got married on December 19, 1974, in Mandaluyong, with the rite presided by then newly instated cardinalJaime Sin.[3]
Jalandoni is a naturalized citizen of the Netherlands, where he resides.[8]