These abuses reportedly took place during the Islamic State's nine-month attempt to repel the Iraqi army's offensive on Mosul.
"During the course of the operation to retake Mosul City, thousands of civilians were subjected to shocking human rights abuses and clear violations of international humanitarian law," said the UN High Commissioner for Human Rights Zeid Ra'ad al-Hussein.
The report, prepared by the UN Assistance Mission for Iraq (UNAMI) and the Office of the UN High Commissioner for Human Rights (OHCHR), documents mass abductions and the use of thousands of civilians as human shields, as well as the murder of people trying to flee the city.
At least 2,521 civilians were killed during the offensive, most as a result of attacks by IS.
"The execution-style killing of civilians, the suffering inflicted on families, and the wanton destruction of property can never be tolerated in any armed conflict, and those responsible must answer for their heinous crimes," said al-Hussein, reports Efe.
In addition to those killed during the hostilities, the Iraqi Civil Defence Corps informed the UN that on October 26, that they had recovered the remains of 1,642 civilians from underneath rubble in Mosul.
The UN Special Representative for Iraq, Jan Kubis, said the report documented evidence of the mass atrocities committed by IS against civilians in Mosul.
"Daesh's reign of terror has spared no one, inflicting untold suffering on unarmed residents whose only guilt is that they lived in the areas under ISIL's control.
"Their evil acts did not stop at killing and terrorizing residents, as they wantonly destroyed cultural and religious monuments, including the city's iconic leaning minaret Al-Hadba, in total disregard of history and Islam, the religion this terrorist organization falsely claimed to represent," he added.
The report also stated that since 2014, 74 mass graves have been found in Iraq _ with varied numbers of corpses, ranging from less than a dozen to thousands of bodies _ and urged authorities to preserve those places as evidence of crimes.
It concluded by calling on the international community, including the UN Security Council, to take action to ensure that those responsible for these crimes are held accountable.
The report also called on the Iraqi government to investigate alleged violations and human rights abuses by the Iraqi army and allied forces, as it recorded 461 civilian deaths as a result of airstrikes during the most intensive phase of the Iraqi offensive.
However, in these cases the UN recognizes that it could not determine the responsibility for the airstrikes.