"Shadi Sadr, a lawyer and women's rights activist, said the nine were convicted of adultery in separate cases in different Iranian cities.
"Their verdicts are approved, and they may be executed at any time," she said, adding that trial protocol was not applied properly in the cases.
Six of the nine were convicted based solely on judges' decisions with no witnesses or the presence of their lawyers during their confessions, she said.
Most of the nine come from areas of Iran that have low rates of literacy and some did not understand the cases against them, she said. One had pleaded guilty to adultery even though she did not know the meaning of the charge.
The nine are between 27 and 50 years old, among them a male music teacher who was convicted of adultery for having an affair with one of his students, the activists said.
"We are trying to stop the implementation of their verdicts. And secondly, we want to amend the country's penal law, in which death by stoning is prescribed," she said.
Under Iran's Islamic laws, adultery in the only capital offence punishable by stoning. Other capital offences in Iran include murder, rape, armed robbery, apostasy, blasphemy, drug trafficking, prostitution, treason and espionage.
The punishment is also applied in some other countries such as Saudi Arabia, United Arab Emirates, Sudan and Nigeria.
A man is usually buried up to his waist, while a woman is buried up to her neck. Those carrying out the verdict then throw stones until the condemned dies.
Stoning was widely imposed in the early years after Iran's 1979 Islamic revolution. But in recent years, it has seldom been applied, though the government rarely confirms when it carries out stoning sentences. The last stoning death confirmed by the government was in July last year."