Danske Bank is closing two branches in Holywood and west Belfast and moving customers to its city centre headquarters, it has announced.
The bank said the branches on Holywood High Street and on Shankill Road will shut on September 12, with their staff being moved to "other roles within the bank".
Its latest closures mean that Danske Bank will have 51 branches in Northern Ireland – nearly half of the 95 it had in 2003.
Customers' accounts will be moved to the bank's headquarter branch in Donegall Square West in the city centre.
The Danish-owned bank last month announced a pre-tax profit of £17.2m over the first three months of this year, compared to a loss of £1m in the same period of 2013.
Tony Wilcox, its managing director of personal banking, said the changes were in response to customers' increasing embrace of online and mobile banking.
He said: "Customers now visit branches less frequently and many are using other convenient ways to bank.
"To keep pace with these changes we continue to increase our investment in alternative banking channels such as telephone banking, online banking and mobile banking."
Mr Wilcox said the news would be "disappointing" to customers but said the bank had written to all affected customers to assure them of the bank's commitment to them.
Customer sort codes and account numbers will not be altered, the bank said. The branches will be put on the market.