The Commonwealth has refused to endorse the July 30 elections saying they failed to meet international standards.
The final report was released by the Commonwealth Observer Group to Zimbabwe which was chaired by former Ghana president John Dramani Mahama.
In the report, Mahama expressed concern over two major issues which he said unfairly unlevelled the playing field in favour of the ruling Zanu-PF.
"The first was the heavy bias of the State print and broadcast media in favour of the governing party. The second was use of incumbency privileges in a manner that unduly disadvantaged opposition parties," Mahama said.
Mahama added that persistent allegations of intimidation reported to the group also tilted the playing field.
"The post-election violence, which resulted in fatalities, and the behaviour of security forces, marred this phase of the elections," Mahama said.
On August 1, six people who were demonstrating against the outcome of the election result were shot dead after soldiers opened live fire.
Mahama described the post-election violence as regrettable and condemned the army's use of excessive force against citizens exercising their right to protest as enshrined in the Constitution.
The group said the use of excessive force against protesting citizens was a setback the elections which had been conducted in a largely peaceful and much improved environment.
Mahama said: "For these reasons, we are unable to endorse all aspects of the process as credible, inclusive and peaceful."
However, the Mahama-led observer group noted that some important gains were made during the election period.
It commended the improved preelection environment where all parties were generally able to campaign freely.
"The polls on July 30 were conducted in a peaceful manner, and were well managed and transparent.
"For the first time, four out of a record 23 presidential candidates were women," he said.
He noted that more needs to be done to improve women's political representation in Zimbabwe.
The group also commended Zimbabweans for their enduring commitment to democracy as reflected in the encouraging voter turnout.
"The group was aware that this report would be considered by the Commonwealth Secretary-General in the membership assessment process," Mahama said, adding that he hopes the report will be valuable in the ongoing assessment of the country's interest to re-join the organisation.
This comes after two American observer groups, the International Republican Institute (IRI) and the National Democratic Institute (NDI) and the European Union in their final reports also refused to endorse Mnangagwa's narrow win saying the elections failed to meet international standards.
Downlowd final report here