The surgery required feathers to be plucked from the penguin's shoulder, leaving a large featherless area.
So before release, she needed to complete her annual moult to replace the feathers as well as pass fitness tests.
Having done both, she was released to the Napier Port sanctuary on Thursday.
Wildbase Hospital and Recovery supervisor Pauline Nijman said native animals often needed specialised skills and knowledge.
"We are very proud to support the aquarium's work in advocating for the plights of our native treasures.
"We hope this penguin will thrive in the wild after getting off to a shaky start."
The little penguin was placed into a quiet safe space, a nesting box on land, which the team hope will give her the opportunity to venture out to sea when she is ready.
General curator at the National Aquarium of New Zealand Joe Woolcott said it was a great outcome.
"It's wonderful to share this moment with other passionate individuals from dedicated organisations working together for this species.
"The kororā sanctuary at Napier Port is the perfect place to get started as it is free from predators and human disturbance."
The sanctuary was developed in 2018 as part of Napier Port's 6 Wharf expansion to help protect the at-risk and declining species.
A total of 150 individual penguins have been microchipped at Napier Port since it opened.
