AIB said it is showing its commitment to its banking operation in the North as it changes the First Trust name back to AIB.
It is the latest phase of a rebranding after the bank gave its operations in the Republic and Britain a makeover in recent years.
The timing of the move is not linked to Brexit, a spokesman said.
The rebranding across the group means the First Trust name will be dropped for its 15 branches, a process that will take two years. It is not saying how much the rebranding will cost.
The First Trust name was created in the 1990s when the bank decided to drop the AIB name for its northern bank, one of the four largest lenders in the North. Like some rivals, it has shrunk the number of branches in the North in recent years.
At the height of the banking and property crisis a decade ago, AIB had proposed selling First Trust but the plan sparked considerable opposition across Ireland.
It will now share the same logo as AIB’s operations in the Republic and Britain.
“Today we are reinforcing our commitment to Northern Ireland with this investment to rebrand First Trust Bank so it aligns with the overall AIB Group,” said Colin Hunt, AIB’s recently appointed chief executive.
“Operating as one brand allows us to enhance our offering to customers across the jurisdictions in which we operate, and unifies us all behind our purpose to back our customers to achieve their dreams and ambitions.”