Permanent TSB is planning to reduce its workforce by around 300, in an effort to cut its costs further.
The redundancies will be achieved by way of a voluntary severance scheme and will mainly target management and head office roles.
The bank currently employs around 2,400 staff in its branches and offices across the country.
As part of the cost-cutting plan, the company also intends to reduce its property footprint.
"We are commencing the Enterprise Transformation Programme to reflect changes which are taking place in the economy and in the way which our customers wish to engage with us," the bank said in a statement.
"The programme will involve a review of the bank's organisation structure, the introduction of smarter ways of working for staff and better use of our property portfolio."
The bank also said the changes will not result in the closure of any of its 76 branches and it will continue to adapt its network to reflect the changes in the behaviour of its customers.
However, because it will have fewer staff and as a result of a move to more flexible ways of working, the lender does plan to leave a building it currently rents on Hatch Street in Dublin.
"We do not intend to renew our lease on our offices in Park Place in Dublin given the ample space available in our other locations," it said.
"We will exit Park Place in April of next year," it said.
The bank said staff and unions have been briefed and further engagement will take place over the coming weeks.
The move by Permanent TSB to reduce its staff numbers follows similar decisions by the other main banks to cut their employee numbers.
Bank of Ireland is to reduce its workforce by 1,450, while AIB also has plans to cut its staffing by 1,500 over the next two years.
Ulster Bank is also reducing its workforce by more than 250 and KBC has closed four "hubs" or branches.
The Financial Services Union, which represents staff at PTSB, said the cuts are a prime example of why a detailed discussion on the future of banking in Ireland is urgently required.
"Today’s announcement is a further erosion of the banking structure in Ireland," said John O'Connell, General Secretary of the union.
"This is occurring without any agreed blueprint for the future of banking."
"The FSU are calling for the establishment of a banking forum both in Northern Ireland and in the Republic of Ireland. Banks are making decisions based on short term profitability instead of long-term strategic planning."
The Government and the Central Bank need to lead the development of a strategic approach to banking which takes account of the needs of all stakeholders."