Amnesty International says Qatar has done "almost nothing effective to end chronic labour exploitation" since it was chosen five years ago to host the football World Cup in 2022.
It says the abuses shame the Gulf state and football's governing body, Fifa.
An estimated 1.5 million migrants work in Qatar, many in the construction boom fuelled by Qatar's successful bid.
Qatar denies exploiting workers and says it has implemented a range of labour reforms.
Qatar's migrant worker population is expected to reach two million within the next two years, Amnesty says.
"Too little has been done to address rampant migrant labour abuse. Qatar's persistent labour reform delays are a recipe for human rights disaster," said Mustafa Qadri, Gulf migrant rights researcher for Amnesty.
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.
A May 2015 report by Amnesty identified nine fundamental migrant labour rights issues.
In Tuesday's report, Amnesty says Qatar has seriously failed to address five of them, including:
Paying wages on time: A wage protection system that requires businesses to pay workers on time by direct bank deposits was signed into law in February 2015, but only came into force in November, with late payment still a widespread problem
Commitment to expanding the labour inspector force to 400 by the end of 2015: postponed until the end of 2016
Reform of the restrictive "kafala" sponsorship system central to the problems faced by migrant workers: limited changes promised in May 2014, only introduced in October 2015, and will not enter into force until the end of 2016
The kafala system currently only allows workers to leave the country or switch jobs with the approval of their employer, and this will not change after the reform comes into force.
Late payment of wages is a widespread problem that leaves migrant workers and their families back home in desperate situations, Amnesty says.
Qatar's labour ministry has declined to comment on the statement, the AFP news agency reports.

Bron: BBC, 1 December 2015. http://www.bbc.com/news/world-middle-east-34972384
Mening: Nadat FIFA meermaals in het nieuws was enkele maanden geleden in verband met de situatie in Qatar, heb ik hier persoonlijk niet meer bij stilgestaan. Nu blijkt dat er helemaal niets veranderd is, en deze situatie betreur ik heel erg. De schuld ligt beide bij de overheid van Qatar en bij FIFA. De locatie voor het organiseren van voetbal WK's wordt gewoon verkocht aan de hoogste bieder. Tot daaraantoe, maar FIFA legt de koper geen voorwaarden op in verband met het respecteren van mensenrechten omtrent de hele organisatie van het WK. Dit vind ik een laffe zet van FIFA, omdat hieruit blijkt dat een hoger bod het misbruik van miljoenen mensen voor hen verantwoordt. De organisatie van een WK heeft een grote (positieve) economische impact op een land. Dat Qatar dit wilt kopen snap ik, maar dat ze zich niet houden aan internationale voorwaarden m.b.t. het behandelen van arbeiders is onacceptabel. De corruptie binnen FIFA blijkt maar weer eens.