They said the work took longer than anticipated due to a number of delays.
Bank manager Julie Holmes was excited to begin work in the refurbished branch.
"We're delighted to be back home in our branch after working from our container over the last two years," she said.
"The container branch has served us well, but it will be nice to have more space to serve our customers comfortably."
She wanted to thank customers in Dannevirke and the wider region for their patience while the work went on.
The branch has a Smart ATM with a Business Deposit Unit available 24/7.
It will be open for over-the-counter transactions on Tuesdays and Thursdays from 10am to 2pm, as well as for booked appointments Monday to Friday.