Around 490 jobs are expected to be cut at Meta's Irish operation.
It is understood the redundancies will impact a number of teams including finance, sales, marketing, analytics, operations and engineering.
Staff at the parent company of Facebook, Instagram and WhatsApp were informed of the job cuts today and a collective consultation process will get under way.
The final number of redundancies will not be known until that process has been completed but Meta has informed the Government that it expects approximately 490 roles to be made redundant.
The number relates to full-time Meta employees in Ireland, not contract workers.
Around 320 jobs were lost at Meta's Irish operation in November and the company currently employs around 2,500 people here.
Today's announcement will not change Meta's overall presence in Ireland, which will continue to be the base of its international headquarters.
The redundancies are part of a global job cuts announcement made in March by Meta CEO Mark Zuckerberg, who said the company's workforce would reduce by around 10,000 people.
Speaking in the Dáil, the Taoiseach described the job losses as significant and said that his "thoughts are with the staff and the families" who are affected.
Leo Varadkar said the Government will engage with the company to ensure decent redundancy packages are given and said that there are now more people working in the tech sector than there were last year.
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He was responding to Labour Party leader Ivana Bacik, who said that "the Government needs to rebalance power between workers and corporations" in light of the further layoffs at Meta, which is "distressing news for so many".
Minister for Enterprise, Trade and Employment Simon Coveney said it was a difficult day for the Meta workers who are losing their jobs and added that the Government stands ready to support them.
He said: "My thoughts are with the people who are impacted but I'd like to give them some reassurance that the tech market is strong, there are more people working in technology companies today than this time last year."
"These are skilled people, they will find other jobs, I think quite quickly."
"We’ve been talking to the company all day and we’ll make sure the redundancy packages are as generous as they can be and if people want to up-skill, re-skill or look at different sectors, the State will be there to support them," Mr Coveney added.
Announcing the global layoffs in March, Meta said that they would impact members of the recruitment division immediately with cuts to follow in late April for Meta's tech groups and in late May for the company's business groups.
March's recruitment division layoffs resulted in around 50 job losses in Ireland and April's tech groups announcement led to less than 20 job losses from Meta's Irish-based data centre team.
Mr Zuckerberg has dubbed 2023 the 'Year of Efficiency' and has pledged to make Meta a leaner, more technology-focused company.
"This will be tough and there's no way around that," he said in a memo staff at the time of the March layoffs announcement.
"It will mean saying goodbye to talented and passionate colleagues who have been part of our success. They've dedicated themselves to our mission and I'm personally grateful for all their efforts," he added.
