Eight million of the children manage at least partly to stay in school and work in their spare time to pay education fees.
Its Programme Manager, Mr Emmanuel Tagwai, made the disclosure in Makarfi, Kaduna state during a sensitization programme to mark the International Child Labour Day.
Tagwai said the figures was from a survey conducted by UNICEF in 2016.
He said eight million of the children manage at least partly to stay in school and work in their spare time to pay education fees.
"Six million working children in Nigeria, equally split between boys and girls, do not at all, while one million children are forced to drop out due to poverty or because of parent’s demand to contribute to the family income."
According to him, many of the children are exposed to long hours of work in dangerous and unhealthy environment carrying too much responsibility for their age.
"Most of them involve in working as under aged girls who serve as street vendors, hawking and guide to their blind parents.
"Traditionally, children have work with their families, learning skills they would need as adult, but today children are forced to work for their own and their family’s survival," he noted.
The programme manager also said most working children have no time, money or energy to go to school.
He therefore called on elected representatives at all level to support the passage of the Child Right Act, and advocate for the ratification and enforcement of international laws that protect children.
Tagwai said that the sensitisation campaign being run in partnership with Christian Aid, was aimed at mobilising local people to combat child labour in the country.