Omar Farouq was convicted of using foul language against Allah during an argument with a friend, according to reports.
The child was sentenced to a decade in jail in a Sharia court in Kano State in northwest Nigeria.
His conviction has been slammed by child rights agency UNICEF, who has called for his sentence to be reviewed urgently.
Kola Alapinni filed an appeal on Omar’s behalf earlier this month. He said his punishment is in violation of the African Charter of the Rights and Welfare of a Child and the Nigerian constitution.
Mr Alapinni said he was working on a similar case when he learned about Omar’s sentence.
The same court sentenced studio assistant Yahaya Sharif-Aminu to death for blaspheming Prophet Mohammed, according to lawyers.
Mr Alapinni told CNN : “We found out they were convicted on the same day, by the same judge, in the same court, for blasphemy and we found out no one was talking about Omar, so we had to move quickly to file an appeal for him.
“Blasphemy is not recognised by Nigerian law. It is inconsistent with the constitution of Nigeria.”
Omar’s mother fled her home after mobs confronted her following the conviction, Mr Alapinni added.
In a statement, UNICEF representative in Nigeria Peter Hawkins said: “The sentencing of this child – 13-year-old Omar Farouk – to 10 years in prison with menial labour is wrong.
“It also negates all core underlying principles of child rights and child justice that Nigeria – and by implication, Kano State – has signed on to.
“This case further underlines the urgent need to accelerate the enactment of the Kano State Child Protection Bill so as to ensure that all children under 18, including Omar Farouq are protected and that all children in Kano are treated in accordance with child rights standards.”
Kano State is one of 12 states in Nigeria that practices Sharia Law alongside secular law, but only muslims can be tried for it.
Sentences vary from amputations to the death penalty.