The Taoiseach Enda Kenny has described the loss of 950 jobs at Aviva "a huge shock".
The insurance giant is to halve its workforce in Ireland over the next two-and-a-half years.
The massive cost-saving exercise will see 950 redundancies from the Irish division of the company and its European business.
The job losses, billed as necessary to make “a stronger, leaner business”, are expected to take effect from next March.
Mr Kenny said: "It is an awful day for the employees of Aviva".
The redundancies are expected to involve 770 from Aviva Ireland and 180 roles from Aviva Europe based in Ireland.
Aviva Ireland employs 1,770 people in Dublin, Cork and Galway and has built up a customer base of 1.3 million people.
Redundancies are expected to be enforced in the next six months.
Mr Kenny said this announcement is a stark reminder of the changes this country has to undergo.
He said: "This is a huge shock to those directly involved.
"It is a stark reminder to everybody of the long road that we have to travel in having our competitiveness put at a level where we can protect jobs across the spectrum and where we can grow our economy to a point where we can have prosperity and opportunity for all our people."