It occupies an area of 4,850 square kilometers extending from the boundary of Zamboanga del Norte on the north to Olutanga Island on the south, from the town of Tungawan on the west to the town Margosatubig on the east boundaries set by Pope John Paul II himself when he decreed the separation of this ecclesiastical territory from the Archdiocese of Zamboanga on December 24, 1979.

The terrain is generally hilly bounded by mountains on the north and the Sibuyan Bay on the south.

A majority of the population are migrants from the Central Visayas area, which accounts for the predominance of the Cebuano dialect, followed by Ilonggo.

In 1933, other ecclesiastical territories were established in Mindanao, separating themselves from Zamboanga, the last of which was the Prelature of Ipil in 1979.

On April 4 of 1995, Ipil was again attacked, this time by breakaway elements of the Abu Sayyaf group.

In spite of these tragedies, the Prelature of Ipil went ahead and celebrated the fifteenth anniversary of its founding in June 1995.

In this regard we believe that we are called to become a true Church of the poor and a community of disciples of Christ as the Gospel teaches, and the Second Plenary Council of the Philippines affirms."

Among its ministries are those on Christian Formation (KRISKA), Catechetics, Family Life, Tribal Filipinos, Youth, Community-based Health Program and Social Action.

On May 1, 2010, Pope Benedict XVI elevated the Prelature of Ipil to a full diocese, the 58th in the Philippines, and appointed as its first bishop Julius Sullan Tonel, who had served as its Bishop-Prelate.