The boys, who had been spirited away from the Kankara Government Science Secondary School in Katsina State in northern Nigeria, were released on Thursday.
State governor Aminu Bello Masari said 344 boys had been handed over to security agencies.
However, many more are feared to still be in captivity, with some accounts alleging that the kidnapping involved upwards of 500 schoolers. Some who managed to escape the abductors have also alleged that some of their classmates died during a jungle trek that followed the kidnapping.
The freed boys were last seen being driven back home to receive medical attention.
They are expected to meet President Muhammadu Buhari on Friday. The head of state has said the boys “endured significant hardships in the course of their ordeal.”