He studied theology at the San Carlos Seminary in Makati; among his classmates were Archbishops Socrates Villegas and Florentino Lavarias.

After returning to the Philippines, he served as Parish Priest in Gapan and became Vicar General and member of the College of Consultors in 2006.

On April 22, 2024, he led the Diocese and other environmental groups in filing a legal petition calling for the closure of the OceanaGold mining concession in Kasibu, Nueva Vizcaya, which was also supported by the provincial government and other organizations.

[6][7][8] In September 2022, Mangalinao successfully underwent coronary angioplasty in a Los Angeles hospital after a myocardial infarction.

[9] In February 2023, he also underwent a quintuple heart-bypass surgery at the Cardinal Santos Medical Center in San Juan, Metro Manila.