[2] Ahmadu Bello, Premier of Nigeria's Northern Region, had offered him a scholarship to study abroad.

[2] In October 1980, Pope John Paul II named Onaiyekan to a five-year term on the International Theological Commission.

[2] Onaiyekan was elected vice-president of the Catholic Bishops' Conference of Nigeria (CBCN) in 1994 and president of that body in 2000.

[2] During the administration of Nigerian president Olusegun Obasanjo, and especially during his second term between 2004 and 2007, Onaiyekan spoke out against the regime for its failure to support democratic principles and its corruption.

Speaking in a service in his cathedral in 2005 with the president in attendance, he called on Obasanjo to resist the temptation to stand for a third term, which the Nigerian constitution did not allow, and asked him to "resist the deadly temptation to want to remain in power perpetually by hook or by crook".

[8] Pope Francis appointed Onaiyekan the Apostolic Administrator of the diocese of Ahiara in Imo State in eastern Nigeria on 3 July 2013.

[9] Pope Francis appointed him to a five-year renewable term as a member of the Congregation for Divine Worship and the Discipline of the Sacraments in October 2016.