At least 117 children, most of them girls, have been used as suicide bombers by Boko Haram since 2014, according to UNICEF.
In the countries fighting Boko Haram in the Lake Chad region - Nigeria, Niger, Cameroon and Chad - 27 children have been used in suicide attacks by the armed group in the first three months of 2017, UNICEF said in a report and statement.
There were nine cases in the same period last year, and 30 children used for bombings in all of 2016, it said.
The Boko Haram campaign is now in its eighth year with little sign of ending, having claimed over 20,000 lives.
The group has increasingly been using children to attack crowded markets, mosques and camps for internally displaced people in northeast Nigeria and the broader Lake Chad region.
"These children are victims, not perpetrators," said Marie-Pierre Poirier, UNICEF's regional director for West and Central Africa.
"Forcing or deceiving them into committing such horrific acts is reprehensible."
One 16-year-old girl from Chad lost her legs after being drugged and forced by Boko Haram to take part in an attempted suicide attack on a crowded market, according to the report.
Though the girl survived, her family initially rejected her "out of fear of stigma". Children who escape Boko Haram are often held in custody by authorities or ostracised by their communities and families.