The Republic of Ireland is to receive €920m (£782m) from a European Commission fund which is designed to "mitigate the impact of Brexit".
The Brexit Adjustment Reserve is available to all European Union (EU) member states "while ensuring a strong concentration on those most affected".
The commission said Ireland is the biggest beneficiary and the first state to benefit.
The reserve has a total budget of €5.4bn (£4.5bn).
The Irish government will receive €361.5m (£307.4m) in 2021, €276.7m (£235.3m) in 2022 and €282.2m (£240m) in 2023.
Commissioner for Cohesion and Reforms, Elisa Ferreira, said Brexit has had a "negative impact on many people's lives" and it is "the people in Ireland who feel it the most".
"The EU's Brexit Adjustment Reserve stands for solidarity with those most affected," she continued.
"In moving forward, we don't want to leave anyone behind.
"The funding that Ireland will receive will contribute to improve living standards, support economic growth in the country and mitigate the negative impacts in local communities."
The Irish government had a prominent role in the Brexit negotiations and in the outworkings of the Northern Ireland Protocol due to its land border with the UK and the potential trade implications of Brexit.
The protocol, designed to prevent trade restrictions at the Irish border, is a key element of the Brexit deal which keeps Northern Ireland aligned with the European Union's single market for goods.
However, it has faced criticism from unionists because of disruption to some goods moving between Great Britain and Northern Ireland.
In November, the Irish government said it was preparing "contingency plans" in the event the UK triggered Article 16, which would in effect allow the UK or the EU to take unilateral "safeguard" measures to suspend parts of the deal.
Tánaiste (Irish deputy prime minister) Leo Varadkar, said nobody wanted "to see the EU suspending the trade and co-operation agreement with Britain".
He said "rebalancing measures" would be needed if the UK took action.