The jihadi, nicknamed White Beard, oversaw the executions of dozens of people during ISIS’s reign of terror in the country.
An Iranian news agency is now reporting the man, formally identified by sources as Abu Omer, has been captured.
The news agency said he had been hiding in Mosul, the former ISIS capital which was finally liberated from the death cult last year.
Civilians in the city told security sources where he was hiding, leading to today’s arrest.
AhlulBayt News Agency said: “Even though the terrorist group is said to have been completely defeated in Iraq, it still scarcely presence in some hideouts across the country.
“The remaining terrorists even continue carrying out assaults on the Iraqi troops and some prominent tribal figures, especially in Kirkuk Province.”
Photographs shared by the news agency show a white-bearded man being led from a police car surrounded by police officers.
Another shows a man taking a selfie with Omer in the background, sitting on what appears to be the front step of a residential building.
Omer is believed to have overseen the cruel murder of gay men in Iraq, who were thrown to their deaths from tall buildings.
He was also pictured watching on as three gay men were publicly beheaded in March 2015.
Other photographs show him inspecting a huge pile of stones ahead of a public stoning.
The arrest symbolises the military defeat of ISIS in Iraq and Syria, where they once controlled an area home to up eight million people.