Reports say that the 17-year-old bomber entered the mosque along with other worshippers and triggered the blast immediately after the prayers. Just last week, the group was blamed for killing 14 people in the Borno state capital, Maiduguri, in what The Associated Press called "one of the largest such attacks in the city in years". Given the seriousness of the injuries, the death toll was expected to rise, he said.
Boko Haram rarely claims attacks but the method is in keeping with tactics seen elsewhere in the long-running conflict.
"Seven Boko Haram on two motorbikes met them and slaughtered two, then killed the other four".
Yan St-Pierre, a counter-terrorism specialist at the Modern Security Consulting Group in Berlin, said the bombing fitted a pattern of previous attacks.
Haruna Furo, head of the Adamawa state emergency management agency, and Musa Hamad Bello, chairman of the Mubi north local government area, both confirmed the attack.
He added: "Mubi is not far away from ... the epicentre of the Boko Haram insurgency".
On November 19, Boko Haram bases in the Njimiya, Parisa and Gulumba areas near the Sambisa Forest of Borno state were hit by air strikes, leading to "heavy losses", he claimed.
He said, "This wanton and deliberate targeting of civilians must end".
But it has been peaceful since the military and the civilian militia ousted them from the town, which is a commercial hub and home to the Adamawa State University.
Boko Haram typically mounts suicide attacks in crowded public places such as mosques and markets.
Boko Haram increasingly has been using teenagers or young women as bombers, many of whom have been abducted.