The President said her prayer during a Mass at the Sunken Garden of the University of the Philippines in Quezon City.
She said the forthcoming international meeting would remind Filipinos to emulate the Blessed Virgin Mary and St. Joseph as a model of "God-loving and humane family."
"Grant your abundant blessing on the Fourth World Meeting of Families, gathered by Pope John Pal II to meet together in or country, so that it may be successful, and serve and protect, and strengthen and develop the Christian family into becoming good news to all families," Mrs. Arroyo said.
"Protect the participants of this meeting with your loving care. Pour down on them the light of your truth, the fire of your love, and the strength of your powers so that everything they do will be pleasing to you and beneficial to families," she added.
The President was accompanied by First Gentleman Jose Miguel Arroyo, daughter Evangeline Lourdes and son Diosdado.
Also in attendance was Quezon City Mayor Feliciano Belmonte Jr.
The eucharistic celebration was led by Msgrs. Esteban Lo and Roberto Canlas.