Bishop Oliver Dashe Doeme of Maiduguri told the Catholic News Agency he had been praying in his chapel when he experienced a vision.
He said Jesus handed him a sword which transformed into a rosary: "I didn't need any prophet to give me the explanation.
"It was clear that with the rosary we would be able to expel Boko Haram."
The bishop said he has been encouraged by the Holy Spirit to spread the message that the Rosary is the key to defeating the organisation and removing them from northeast Nigeria.
The bishop has reported that in the Maiduguri diocese, where Boko Haram has been active, there were about 125,000 Catholics in 2009.
He claims that number has dropped to around 50,000 to 60,000 due to the high numbers of families fleeing the region.
