Over 372,000 households in receipt of the fuel allowance are to be paid an extra €125 from today, Monday.
The Government decided to add the sum to the payment in an effort to combat the rising cost of living brought on by Russia's invasion of Ukraine.
Depending on their social welfare scheme, recipients will receive the payment into their bank account this week.
The payment will be once-off and is means-tested.
Pensioners, widows, widowers, jobseekers, lone parents and people with disabilities will be eligible for the payment.
The move is part of the Government's €505 million package to mitigate the effects of rising energy costs in Ireland.
In a press statement, Minister for Social Protection Heather Humphreys said she was "acutely conscious that the rising cost of living is causing considerable concern for families".
"We have all felt it in recent months – through our bills, at the petrol station and in the supermarket", Humphreys said. "And unfortunately, the situation is not being helped by the horrific war unfolding in Ukraine.
"This once-off payment is part of a wider package of measures, totalling €505 million, agreed by Government last month in order to make things a little easier for families."
She added: "This €125 lump sum fuel allowance payment is aimed at the most vulnerable people in our society, to ensure that they are protected against rising fuel costs.
"Government also responded last week by cutting excise duty on petrol and diesel, which has become the source of considerable concern for motorists in recent months."
The package also included a €200 reduction in energy bills, which is coming into effect this month.
The payment was doubled to €200 after it was agreed that the original amount of €100 was not enough due to increases in the cost of living .
Around 2.25 million account holders will benefit from the scheme, with the money due to be deducted from bills automatically.
The Government has confirmed that the €176.22 credit line (ex VAT) will start appearing on bills from April and continue over the following month.
The credit will be applied automatically. Households do not need to apply for it. They do not need to contact their electricity supplier.
