Razieh Ebrahimi was married at 14, had a child at 15, shot her husband at 17 and is now on death row aged just 21.
Charities including Human Rights Watch are fighting to have her sentence repealed and hold it up as an example of brutal capital punishment in Iran and other countries.
International law prohibits the execution of child offenders but in Iran, girls as young as nine and boys aged 15 or older can be killed for some crimes, including murder.
Authorities arrested Ebrahimi – called “Maryam” in the local press – four years ago after she shot her husband in the head as he was sleeping and buried his body in the garden, a source told Human Rights Watch.
Imprisoned in the city of Ahvaz, she admitted guilt and said she snapped after several years of physical and verbal abuse at the hands of her husband.
Joe Stork, the deputy Middle East and North Africa director of Human Rights Watch, said the execution order should be reversed.
He added: “Every time an Iranian judge issues a death sentence for a child offender like Ebrahimi, he should remember he is flagrantly violating his legal responsibilities to administer justice fairly and equitably.”
Prison authorities reportedly attempted to carry out her execution earlier, but when she told them she was 17 when she killed her husband they returned her to her cell.
Following recent changes to Iran’s penal code, her lawyer requested a retrial from the Supreme Court on the basis that she had been under 18 and did not understand the consequences of her actions but the court refused.
In an interview with an Iranian online magazine, Ebrahimi’s lawyer, Hassan Aghakhani, said he hoped the judiciary could at the very least suspend his client’s sentence until all branches of the court applied laws on child executions uniformly.
Human Rights Watch is calling on the Iranian government to prohibit the death penalty for under-18s and impose a moratorium on all passed sentences.