Parents raised and paid an undisclosed ransom to free the students, who were among more than 100 taken on July 5 from Bethel Baptist High School, officials say.
Bandits have released 15 more students kidnapped last month from a Baptist school in northwest Nigeria, officials said.
Parents had raised and paid an undisclosed ransom to free the students, who were among more than 100 taken on July 5 from the Bethel Baptist High School, school administrator Reverend John Hayab told Reuters news agency on Sunday.
"The students are already being released and would be handed over to their parents any moment from now," Hayab said.
Hayab previously said the abductors were seeking 1 million naira ($2,430) per student.
Kaduna state's commissioner for internal security, Samuel Aruwan, confirmed the release but did not immediately comment on the ransom payment.
Dozens still in captivity
Kidnappers released 28 children from the school in July following the release of a first group of 28 two days after the raid. Around 80 had remained in captivity before Sunday's release.
Armed bandits seeking ransoms have abducted more than 1,000 students from schools in northwest Nigeria since December, and Kaduna state schools remain closed due to the threat.
President Muhammadu Buhari in February called on state governments to stop paying bandits, and Kaduna Governor Nasir El Rufai publicly refuses to pay.
But desperate parents and communities often raise and pay ransoms themselves.