Danske Bank agreed to acquire Northern Bank and the National Irish Bank for £967m in 2004 and has since invested around £100m in Northern Bank.
Commuters in Belfast were first to catch a glimpse of the new Danske Bank branding around its head office in Donegall Square West, after signage was unveiled last night.
Danske Bank signs will go up above the doors of every branch and finance centre over the next fortnight.
However, Northern Ireland is not alone - all brands within the Danske Bank Group will today begin to change their names, including banks in Norway, Finland, Latvia, Estonia and Lithuania.
Customers' account numbers, sort codes and general account facilities will remain unchanged by the rebrand and new Danske Bank branded cheque books, debit cards and credit cards will be issued on renewal.
From mid-2013, Danske Bank branded notes will start to be issued, although Northern Bank branded notes will continue to be circulated and will continue to be accepted in retail outlets.
The bank's website has changed to www.danskebank.co.uk and other changes will include the use of Danske Bank instead of Northern Bank in product names.
Head of Danske Bank UK and Ireland Gerry Mallon (below), who was appointed to the position in 2008, has overseen major parts of the rebrand and said that the switch was reflective of major changes - both in the banking sector and in society as a whole.
"Understandably there may be some sadness around saying goodbye to the Northern Bank name, which has been part of the fabric of local life for over 200 years," Mr Mallon said.
"However, supporting customers with expertise and local knowledge (that has been) built up over the years will remain at the very heart of our business.
"For seven years now, customers have been experiencing what Danske Bank Group has to offer and year after year we have continued to invest in the services we offer our customers.
"The most recent Danske Bank addition has been the launch of our tablet banking app - a first in this market.
"Our change of name gives us a unique opportunity to create an even better bank for our customers," he added.
Highs and lows through the centuries
In 1809, Northern Bank began as a Belfast-based bank known as the Northern Banking Partnership. It opened its first branch in the Republic in 1840.
In 1970, the Northern Banking Company Limited amalgamated with the Belfast Banking Company Limited to form what is now known as Northern Bank Limited.
Until 1988, the bank was a subsidiary of the Midland Bank.
In 1986, the bank's operations in the Republic of Ireland were separated from its Northern Ireland business into a subsidiary, Northern Bank (Ireland) Limited.
In 1988, both Northern Bank Limited and Northern Bank (Ireland) Limited were acquired by National Australia Bank, after which the operations in Northern Bank (Ireland) Limited were renamed National Irish Bank.
In December 2004, Danske Bank bought Northern Bank (and National Irish Bank) for £967m.
In 2005, the Danske Bank Group acquired the bank. National Irish Bank was separated from Northern Bank.
Following the £26.5m robbery in 2004, Northern Bank announced on January 7, 2005, that all its notes were to be recalled and reissued.
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