The London-based organisation said the reintroduction of the death penalty when authority was handed to Iraq's government in 2004 was "a profoundly retrograde step" which had done nothing to deter insurgency in Iraq.
AI also claimed that those sentenced to death are often subject to torture and trials which do not meet international standards of justice, calling for an end to capital punishment in the country.
"This represents a profoundly retrograde step and one that should not be overlooked simply because far larger numbers of lives have been lost due to ongoing violence," the report said.
"The death penalty is a cruel, inhuman and degrading punishment and the ultimate violation to the right to life; furthermore, it is not an effective deterrent against violence and crime, as the continuing crisis in Iraq underlines."
Saddam Hussein, the former Iraqi leader, was among those executed last year, leading to criticism from many including chancellor Gordon Brown.
"It was entirely predictable that the restoration of the death penalty would ... perpetuate and exacerbate the abuse of human rights and come to be seen, as in the case of Saddam Hussein's execution, as an instrument of vengeance far removed from any notions of justice," the charity said.
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