Cardinal John Ribat, M.S.C., Metropolitan Archbishop of Port Moresby, Papua New Guinea, was born on February 9th, 1957, in Volavolo, archdiocese of Rabaul, Papua New Guinea. After attending elementary school in Naveo and Volavolo, he attended the Malabunga Government High School in Rabaul. He completed high school at the St. Peter Chanel High School of Ulapia and entered the Congregation of the Missionaries of the Sacred Heart, where he made his first profession on February 2nd, 1979. He studied philosophy and theology at the Holy Spirit Seminary of Bomana and was ordained a priest on December 1st, 1985.

From ordination until 1991 he exercised his pastoral ministry in various parishes in the diocese of Bereina; he then followed a training course at SAIDI Centre in Manila, and was Master of Novices from 1992 to 1996. In 1997 he served as parish priest and from 1998 to 2000 was Master of Novices in Suva, Fiji Islands.

On October 30th, 2000, he was elected to the titular see of Macriana minor and appointed auxiliary bisop in the diocese of Bereina, Papua New Guinea. He received episcopal ordination on February 11th, 2001.

On February 12th, 2002, he was appointed bishop of Bereina.

On April 16th, 2007 Benedict XVI appointed him as coadjutor archbishop of Port Moresby and on March 26th, 2008, he became archbishop of the metropolitan see.

He served as president of the Episcopal Conference of Papua New Guinea and Salomon Islands from 2011 to 2014.

Since 2014 he has held the role of Chairman of the Federation of Catholic Bishops Conferences of Oceania (FCBCO).

On 14 July 2018, the Holy Father Francis appointed him President Delegate of the XV Ordinary General Assembly on Young People, the Faith and Vocational Discernment (October 2018).

He is Papua New Guinea's first cardinal.

Created and proclaimed Cardinal by Pope Francis in the consistory of 19 November 2016, titular church of San Giovanni Battista de' Rossi.