Core banking systems are back up and running for customers, Kiwibank says.
It follows Kiwibank's confirmation of "continued intermittent issues" on Monday, in which some customers were unable to access the app, internet banking and website, and experienced delays getting through to the call centre.
In a statement issued on Tuesday, a Kiwibank spokeswoman confirmed a system fix was implemented overnight.
Transactions, including salary and wage payments, were processed as normal on Monday night, the bank said.
"Any automatic payments, government, salary and wage payments overnight were not affected," the spokeswoman said.
"Again, our apologies to any customers inconvenienced yesterday."
It follows an update to Kiwibank's Facebook page on Tuesday morning, in which the bank confirmed a fix had been implemented.
"We’re continuing to monitor our systems and want to thank you for your patience and understanding as our teams worked to urgently resolve the issue," the post reads.
"We are aware of the inconvenience this caused for many of our customers and apologise for this."
Comments on Tuesday's post showed customers were generally supportive.
"Great stuff Kiwibank as long mine [sic] APs gone out, I'm happy customer," one person said.
"Hey, these types of things happen to everyone at some point. Thank you for the update and keeping us all informed," said another.
Any customers still experiencing issues could send a secure mail to the bank via the Kiwibank app or internet banking. Alternatively, customers could call 0800 113 355, or email email@example.com.