He worked as a parish priest, continued his studies in Manila, and served as master of novices for the Missionaries in Suva, Fiji.[1]
On 30 October 2000, Pope John Paul II named him auxiliary bishop of Bereina and titular bishop of Macriana Minor. He was consecrated bishop on 11 February 2001 and named Bishop of Bereina on 12 February 2002. Pope Benedict XVI named him Coadjutor Archbishop of Port Moresby on 16 April 2007 and he succeeded to that office on 26 March 2008.
On 9 October 2016, Pope Francis announced that he planned to raise Ribat to the rank of cardinal at a consistory scheduled for 19 November 2016.[3] He was made a Cardinal Priest on that day and assigned to the titular church of San Giovanni Battista de Rossi.[4] He is the first cardinal from his country.