Scottish-based pensions and investments company Standard Life is to move more than €19bn in assets to Ireland.
The decision by followed a court ruling in Edinburgh, which gave final approval for the transfer of stg£17bn in assets to Dublin-based Standard Life International.
The firm has said this will "ensure continuity of service for Irish customers when the UK leaves the European Union."
Nigel Dunne is CEO Standard Life International.
He said: "On behalf of our customers, we are delighted with the positive court ruling.
"It allows us to ensure a seamless continuity of service for all our clients which has been our top priority since the 2016 Brexit referendum.
"Customers will not be inconvenienced and don't need to take any action, there will be no noticeable difference from their perspective in any Brexit outcome".
Around 600,000 Irish, German and Austrian Standard Life customer policies will legally transfer to Standard Life International in Dublin to avail of EU passporting rights post-Brexit.
The company said it has hired some 20 additional staff to support the business in areas of risk, finance and actuarial services.
Its operations in Ireland will see a combined total of €26bn worth of assets under administration with the transfer from the UK.
The company added that it is set to become the second largest life company serving domestic customers in Ireland post-Brexit following this ruling.