Auckland cat charity Lonely Miaow, who is now caring for the kittens, said the animals were found in a state of severe distress and in need of urgent medical attention.
The kittens weighed barely 400g and are about 4 weeks old.
"They had been dumped in a plastic box, seemingly left to die," Lonely Miaow cat care manager Kella Sanford-Clark said.
"This suffering is unnecessary and avoidable. So we hope these images make people think twice about making sure their pet is desexed.
The kittens had badly infected eyes when found in a plastic box in South Auckland on November 14. Photo / Supplied
"With kitten season now well under way, the state of these kittens is the reality of what our volunteers will be dealing with week in, week out for the next few months.
"Our vision is for Auckland to be a city without uncared-for stray and abandoned cats. The only way this can happen is if more pet owners step up to the plate and start spaying and neutering their animals."
Volunteers at Lonely Miaow are now treating the kittens and are urging Aucklanders to desex their cats.
A Givealittle page has been set up to raise funds for the kittens' medical treatment.
The kittens, just a few weeks old, were found in severe distress in a Mangere park. Photo / Supplied