Police said a teenage bomber targeted the mosque in the town of Mubi, Adamawa state, as people arrived for morning prayers on Tuesday.
There was no immediate claim of responsibility, but armed group Boko Haram carries out regular attacks in the region.
“It was a devastating attack on the mosque as people gathered for prayer,” said Al Jazeera’s Ahmed Idris, reporting from Nigeria’s capital, Abuja.
“The number of wounded was so high that we will probably see more and more people succumbing to wounds.”
He added: “Mubi is not far away from … the epicentre of the Boko Haram insurgency.”
Boko Haram’s eight-year armed campaign in the region has killed more than 20,000 people and forced up to 2.7 million to flee their homes.
Idris said emergency workers, who are usually based in state capital Yola, had to travel for several hours to reach Mubi, some 200km away, because of the bad roads in the area.