In a briefing on Friday, the country's leader, Taoiseach Micheál Martin, asked the Irish public to draw on its "spirit of resilience and...solidarity" as he outlined the new restrictions.
The rules will be imposed from December until January 9, meaning socialising over the Christmas and New Year's period will be restricted.
What rules are changing?
Nightclubs will close
Pubs, restaurants and hotels will be restricted
Covid passes will be required for gyms, leisure centres, hotel, bars and restaurants
Entertainment, cultural, community and sporting events cannot operate at over 50% capacity
Private home visits must involve no more than four households
Nightclubs, which reopened a month ago for the first time since the start of the pandemic, must remain closed while large events will be curbed at 50% capacity.
Bars, restaurants and hotels must close at midnight and a maximum of six adults can be seated at one table. Additionally, multiple table bookings will banned, customers must socially-distance and only table service will be allowed.
The Institute of Public Health has advised that visits to private homes over the coming weeks should be kept to a maximum of three other households at any one time. However, it acknowledges a "need for flexibility".
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Ireland has reported one case of the Omicron variant, which was first reported by South Africa last week.
Over the past seven days, there was Ireland 31,155 confirmed cases of Covid in Ireland and 55 related deaths.
The Taoiseach recognised that many will be disappointed and frustrated by the new restrictions, not least those in the hospitality and entertainment industries.
"I want to reassure them that just as we have done since the beginning of the pandemic, the government will stand by them and ensure that they have the financial supports necessary to weather this latest storm and to stay intact until we are out of it," he said.