Issa al-Nuaimi told AFP that the "temporary minimum wage of 750 riyals ($195, 166 euro) per month will immediately come into effect", while officials work on setting a permanent rate.
In addition to the new salary, labourers will receive free accommodation, food and healthcare plans, covered by employers, he said.
Introducing a minimum wage was among a package of major labour changes announced last month by Qatar, which has come under continued global scrutiny and criticism for its treatment of some two million migrant workers.
Qatar has never before had a minimum wage policy, and officials said the 750 riyals figure could increase after a review. "We will not approve any employment contract if the salary is below 750 Qatari riyals per month. All contracts must now be approved by the ministry (of labour)," Nuaimi said.
"If any change is made to the contract, we will apply the new procedures."
He added that the new wage limit had been enforced for the past month.
Since being controversially chosen to host the World Cup, Qatar -- which is spending $500 million a week on the tournament -- has been routinely accused of forcing workers to toil in conditions critics have likened to modern-day slavery.
Among other key reforms on the books are a requirement to lodge job contracts with the government, preventing changes to contract terms after the arrival of workers in Qatar, and ending the right of employers to stop staff from leaving the country or changing jobs.
The package was enough to satisfy the UN's International Labour Organisation, which on November 8 said the reforms matched up to its expectations for labour rights.
As a result, it also abandoned any plans to order a potentially embarrassing inquiry into Qatar's treatment of workers.
Unions and rights groups, previously among Qatar's biggest critics, have also backed the changes but some question whether Doha will live up to its promises.
Nuaimi said it would, insisting that: "Qatar's pledge does not end here. This is a long-term commitment and we will make further improvements."
He added that migrant workers were "part and parcel" of Qatar.
"All these are not promises but real facts because we are convinced that is what we should implement," said the minister. "It's not just promises."
The overhaul comes as Qatar finds itself at the centre of a bitter regional crisis threatening to destabilise the Gulf.
Led by Saudi Arabia, a quartet of Arab states in June cut ties with Qatar over its alleged support for terrorist groups and relations with Iran. Doha denies the charges.
Mustafa Qadri, executive director of Equidem, a human rights research organisation, called the minimum wage "an important step".
However, he added: "On immediate reflection the amount of 750 seems low given the high cost of living in Qatar, and that so many if not most workers pay large recruitment fees at high interest.
"It would take most workers several months to clear their recruitment loans on that minimum wage amount."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)