John Onaiyekan, an haife shi a ranar 29 ga watan Janairu a shekara ta 1944, a garin Kabba wanda ayanzu tana jihar Kogi, daga iyayensa Bartholomew da Joann Onaiyekan. Yayi makarantar St. Mary's Catholic School dake garin Kabba daga shekara ta 1949 zuwa 1956, sannan kuma yaje Mount St. Michael's Secondary School dake Aliade, jihar Benue, daga shekara ta 1957 zuwa 1962, da kuma St. Peter & Paul Major Seminary in Bodija, Ibadan, a shekara ta 1963 zuwa 1965. Ya kammala karatun addininsa a kasar Rome a shekara ta 1969 kuma aka jagoranta shi a matsayin priest a 3 ga watan Augusta wannan shekara daga Auguste Delisle na garin Ilorin. Ahmadu Bello Sardaunan Sokoto, firimiya Arewacin Nijeriya yabashi tallafin zuwa karatu a kasar waje. Onaiyekan ya koyar a makarantar St. Kizito's College, Isanlu, a shekara ta 1969. Yazama rector of St. Clement Junior Seminary dake Lokoja a shekara ta 1971. Ya kuma zama Rector a makarantar Ss. Peter & Paul a shekara ta 1977.