He served as a Parochial Vicar in Nandom and as assistant director of catholic schools in the diocese of Tamale. He has also served as parish priest, as Vicar General of the diocese and Administrator of the Cathedral.

On 3 November 1959 the diocese of Wa was erected and on 16 March 1960 he was appointed the first Bishop. He received episcopal ordination on 8 May 1960.

He was the first to introduce liturgical inculturation into his diocese and founded numerous schools and a minor seminary.

In 1972 he was appointed Apostolic Administrator of Tamale, and for two years carried out his duties in both dioceses until he was appointed bishop on 18 November 1974. When Tamale was raised to an archdiocese, he was named the first Archbishop on 30 May 1977.

He has also served as a member of the Pontifical Council for the Laity and as president of the Bishops’ Conference of Ghana. He was also coordinator of the pan-African Council of the Laity.

Archbishop emeritus of Tamale, 26 March 1994.

Created and proclaimed cardinal by Benedict XVI in the consistory of 24 March 2006, of the Deaconry of Sant’Elena fuori Porta Prenestina (St. Helena fuori Porta Prenestina).

Cardinal Peter Poreku Dery died on 6 March 2008.