The council backed the bylaw change after receiving 1412 public submissions discussing the options for better cat management in the district.
The vast majority of submissions supported mandatory desexing, microchipping and registration. A much lower number backed an amendment that would limit the number of cats allowed per property.
Councillor Tricia Cutforth said the council previously lacked "a lot of muscle" to their "arm" when it came to dealing with residents with an excessive amount of cats creating a neighbourhood nuisance.
But that would now change with the district council stepping up to take action over cat management in the absence of any national legislation.
"It gives us a little bit more of an opportunity to try to make a difference in terms of what we can do," Cutforth said.
But she noted the change doesn't take responsibility away from individual cat owners.
Councillor Anna Murphy, who claimed people "jumped down her throat" when she tried to tackle the issue of cat control back in 2017, echoed Cutforth's sentiments.
"This is just a little piece of the jigsaw," she said.
The main piece to the puzzle, according to Murphy, was the public's awareness and understanding about the importance of desexing and microchipping their cats.
Councillor Carol Peters was pleased the council was taking a step towards Whangārei becoming more "ecologically special" by managing the unofficial but notorious predator.
Cats were somewhat controversially left off the target species list for Predator Free 2050 which aims to protect the country's native flora and fauna.
New Zealand's oldest and largest animal welfare charity, the SPCA, praised the district council's decision to act in favour of animal welfare.
SPCA scientific officer Christine Sumner said the country's unwanted cat population had to be viewed as a public problem.
"[...] requiring local and national policy solutions where "the true cost of owning an un-desexed and microchipped cat is not an undue burden on New Zealand society."
Sumner said caring for unwanted cats - whether in a shelter, rescue, or council service - came at a large financial cost.
While prices vary, desexing a cat can cost between $80 to $150. However, the SPCA provides subsidised Snip 'n' Chip opportunities that cost $10.
In March this year, 600 Snip 'n' Chip vouchers were made available to Whangārei cat owners with funding provided by the Whangārei District Council.
Snip 'n' Chip national desexing programme manager Rebecca Dobson said desexing and microchipping were known to make a real difference for animal welfare in New Zealand.
"Desexing your pet will help them lead a happier and healthier life and has so many other benefits," she said.
"It ensures the cycle of unwanted litters is broken and people's companion animals don't unknowingly or unexpectedly reproduce more litters of animals, as well as protects our wildlife."
Dobson emphasised how microchipping pets gave owners the best chance of being reunited with them if ever they became separated.
Whangārei District Council's change to the Animal Bylaw follows suit with the Whanganui District and Palmerston North City councils.
Both already passed their bylaws with compulsory microchipping, and desexing. However, they went a step further with a three cat household limit.
The Advocate has approached the council for further information about how long cat owners have to comply with the change to the bylaw and for any other key information.