Lawyer Abdolsamad Khoramshahi said Khadijeh Shahla Jahed was hanged at Evin prison in Tehran after her guilty verdict was confirmed by Iran's Supreme Court and Judiciary Chief Ayatollah Sadeq Amoli Larijani, the government-backed Press TV reported.
Jahed was convicted in the 2002 stabbing death of Laleh Saharkhizan, wife of former soccer striker Nasser Mohammadkhani. Jahed lived with Mohammadkhani in the 1980s under a temporary marriage arrangement.
Amnesty International condemned the Iranian authorities for carrying out the execution of the woman known as Shahla.
"Shahla Jahed's execution, like all such executions, is an example of premeditated and cold-blooded killing by the state, and is particularly distressing as there were serious concerns over the fairness of the trial, and the evidence used against the defendant." Malcolm Smart, Amnesty International's director for the Middle East and North Africa, said in release.
The human rights organization said Iranian media reported Saharkhizan's brother kicked away the stool on which Jahed stood with the noose around her neck. Under Iranian law, the victim's family in a murder case has the right to either insist on execution, in which they can participate, or pardon the perpetrator and accept compensation.
Jahed confessed to the murder in court but later retracted her statement, saying, "everyone knows the conditions I confessed under," raising concerns her confession may have been coerced, Amnesty International said.