"The abuses against migrant workers in the construction sector in Qatar are grim," the report said.
Qatar hosts the 2022 World Cup soccer tournament.
The United Nations says Qatar has the highest ratio of migrants to citizens in the world.
The advocacy group said it spoke with migrant workers who suffered "severe psychological distress" not only because of the abuses but because they felt powerless to resolve the situation on their own.
AI offered six pages of recommendations to the International Federation of Association Football, known also as FIFA, and the Qatari government on how best to address the situation.
"Only fundamental change, including bold reforms backed with political will from the very top of the government, will address the issues documented in this report," the organization said.
FIFA Secretary-General Jerome Valcke said in an October letter to Amnesty International that the sporting body shares its concerns and felt the World Cup was a positive venue for reform. Letters from the Qatari government expressed similar consideration for Amnesty International's views on migrant workers' rights in the country.
Francois Crepeau, U.N. special envoy on the human rights of migrants, issued a similar plea to the Qatari government last week.