Many were abandoned when owners went on holiday, or sacrificed as finances were stretched, Dunedin Cat Rescue director Sarah Davey said.
She expected dozens of cats and kittens to be neglected, abused or dumped in Dunedin in the coming weeks.
''It's a mixture of it being kitten season and people going away and leaving their cats without someone to feed and love them, or just dumping them.
"At Christmas time, everyone's under financial stress, so a lot try to get rid of their cats because they don't want to spend money on them or can't afford to keep them.''
Dunedin Cat Rescue's foster programme was already at capacity and she urged cat owners to be more responsible and think twice about their feline friends.
''At the moment, we've got 33 cats with us and all our fosterers are at full capacity; there's not one that's free to take more cats or kittens.''
Three 8-week-old kittens rescued on Monday night were the latest additions to Ms Davey's household.
She had adopted four rescued cats since starting the incorporated society in November last year. In that time, the group had rescued about 200 cats.
Dunedin Cat Rescue was to become a charitable organisation, but until then it relied on community donations. ''We can only do as much as what we get in support, so we really encourage people to care for their pets and use us as a last resort before euthanasia,'' she said.
Rescued cats and kittens were fostered until they were healthy and sociable enough to be put up for adoption.
Ms Davey said Dunedin Cat Rescue, which she ran with the help of Rach Bond and Rachel Moth, had a good relationship with the Otago SPCA, although the organisations were separate.
She could be contacted, about cats and kittens abandoned or for surrender, by email (sarah@dunedincatrescue.org.nz).
