According to witnesses, the woman was publicly executed in the Sablaale district of the lower Shabelle region, some 250 kilometres (155 miles) from Mogadishu. The area is under control of the Islamist group.
“The judge… said that the woman has confessed to the charges against her, that she married 11 husbands at the same time,” read a statement carried on a pro-Shabaab website.
Witnesses, who declined to be named, said a dozen hooded Shabaab fighters were involved in the stoning.
According to the Shabaab statement, the 30-year-old mother of eight was arrested after two men argued over her, each claiming to be her legal husband. After her arrest the number of men claiming to have married her increased.
“One of the husbands died and another divorced her, but nine others were still married to her,” the statement added.
Witnesses said the woman married the men secretly and that none of them were aware of her prior marriages.
While a Somali man — who can marry up to four wives — sometimes marries secretly to hide a union from one of his other spouses, this is far less common among women.
However, it does occur that a woman will take a second husband without an official divorce, often for economic reasons.
Soldiers from the African Union Mission in Somalia (AMISOM) pushed the Shabaab out of the Somali capital in 2011, subsequently ousting them from other cities and towns.
But the Islamists still hold sway in large parts of the countryside where they often carry out stonings for adultery.