An outage saw transactions affected for customers
AIB says all its services are now operating as normal.
It comes after earlier technical issues meant transactions were affected for customers online, in branches and on phones.
The bank said customers could continue to withdraw cash from ATMs and make purchases in store and online with their AIB cards.
An earlier update from the bank had said services were operating as normal, with the exception of its mobile banking service.
The bank has apologised for the inconvenience caused to customers.
It has also moved to assure customers they will not be out of pocket as a result of the incident.