John Olufemi Onaiyekan, the archbishop of Abuja, was one of six non-European prelates nominated by the pope to the elite body that remains heavily weighted in favour of Europe.
"I see the elevation as a great honour to Africa, Nigeria, my country and (Nigeria's capital) Abuja," the 68-year-old told AFP by phone from Rome.
"It is an encouragement for me to continue the good works that I have been doing for humanity," he added.
Onaiyekan has won widespread respect for his efforts to ease religious tensions in Africa's most populous nation, where divisions have led to deadly clashes.
He has used the pulpit to speak against misgovernance and build bridges between Islam and Christianity in a country almost evenly divided between the two faiths.
With Nigeria facing a deadly insurgency by Islamist extremist group Boko Haram, a number of Evangelical leaders have ominously raised the possibility of Christians being forced to defend themselves.
Onaiyekan has however been a voice of reason and has urged calm, saying Boko Haram extremists were not representative of average Muslims in the country.
He co-chairs a key inter-religious forum with Nigeria's top Islamic leader, Muhammad Sa'ad Abubakar.
Joseph Faniran of the Catholic Institute of West Africa told AFP Onaiyekan "richly deserves" the appointment.
Onaiyekan, who holds a doctorate in biblical theology, was ordained as a Catholic priest in 1969 and appointed by the late Pope John Paul II as a permanent member of the Synod of Bishops in Rome.
American James Michael Harvey, Lebanon's Bechara Boutros al-Rahi, India's Baselios Cleemis Thottunkal, Colombia's Ruben Salazar Gomez and Filipino Luis Antonio Tagle, were the other prelates named to the College of Cardinals on Wednesday.