In a damning indictment, the human rights group said the lack of substantive change "shames" the gas-rich Gulf state and FIFA, football's governing body.
Its statement was published to coincide with the controversial decision taken on December 2, 2010 to allow Qatar to host world sport's biggest tournament.
"Despite massive public exposure of the appalling conditions faced by most migrant construction workers, the Qatari authorities have done almost nothing effective to end chronic labour exploitation," Amnesty charged.
The rights group urged FIFA officials and the World Cup's major sponsors to press for change before it is too late.
Mustafa Qadri, Amnesty's Gulf migrant rights researcher, said: "Too little has been done to address rampant migrant labour abuse.
"The reforms proposed by the government fail to tackle the central issues that leave so many workers at the mercy of employers, yet even those changes have been delayed.
"Unless action is taken -- and soon -- then every football fan who visits Qatar in 2022 should ask themselves how they can be sure they are not benefiting from the blood, sweat and tears of migrant workers."
Amnesty said Qatar had failed to make changes in several key areas, including giving workers the freedom to change jobs, to leave the country and the right to join unions.
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"Limited progress" had been made in only two areas out of nine: wage payment and health and safety, it said.
It quotes one construction worker, "Ramesh", who told Amnesty what happened after he complained to his boss.
"I went to my manager's office and told him I want to go home because my pay is always late. The manager screamed at me, saying, 'Keep working or you will never leave!'"
In May, Amnesty already accused the authorities in Doha of "promising little and delivering less" on labour reform.
There are about 1.8 million foreign workers in Qatar, many working on major infrastructure projects directly or indirectly related to the World Cup.
That number is expected to top two million in the next few years.
In October, Qatar announced changes to its much-criticised "kafala" labour system of sponsorship -- which currently only allows workers to leave the country with the approval of their employer -- as well as regulations that allow workers to switch jobs at the end of their contract.
It is not clear yet when these reforms will come into force.
Earlier this month, Qatar also introduced a Wage Protection System to ensure migrant workers get paid on time.