Eamon Martin delivered a call for renewal in the Church as he was ordained into an interim post ahead of eventually succeeding current Primate of All Ireland Cardinal Sean Brady.
The Derry-born former teacher became Coadjutor Archbishop of Armagh and will act as an assistant to Cardinal Brady for at least another two years.
The 52-year-old takes up his new post after a period of unprecedented turmoil for the Church in Ireland, during which its influence has been damaged by a series of clerical child abuse scandals.
At his ordination ceremony in St Patrick's Cathedral in Armagh - during which a letter endorsing his appointment signed by former Pope Benedict was read to the congregation - the new Coadjutor Archbishop reiterated his belief that the time had come to "sing a new song to The Lord".
"Of course there are some who will not want to listen," he said. "There are others too who have been so hurt and betrayed in the past that understandably they find themselves unable to trust our message. That is why we must continue, as Pope Benedict XVI exhorted us in his letter, 'to reflect on the wounds inflicted on Christ's body', and persevere in our efforts to bind those wounds and heal them."
Archbishop Martin said he felt a whole mixture of emotions on being chosen to take up the role. "Excitement, nervousness, a sense of my unworthiness and inadequacy," he said.
The cleric then referred to Pope Francis's call for the Church to reach out to people. "Pope Francis has spoken recently about the need to 'go out of ourselves', beyond our usual comfort zones to the 'edges of our existence'," he said.
"It is there, he says, that we meet the poor, the forgotten, the disillusioned. And there we must sing our new song in a way which will speak to the reality of their daily lives, with all their hurts and burdens and troubles. The only way we can do that is by singing about God's mercy and love for each one of us personally.
"That is what the new song is about - it is a song of love, that God unconditionally loves each one of us, despite our sinfulness and imperfections, and that the Lamb of God, who suffered and died to take away the sins of the world, has mercy on us."