September has been chosen for the $7000 initiative from Queenstown Cat Rescue, as warmer temperatures will assist the cats' recovery.
The money was raised through various fundraising efforts by co-founders Ruth de Reus and Julia Milley, together with trustee Mayumi Rowcroft and several other volunteers.
Ms de Reus said the campaign would be advertised locally.
The advertising notice said the group had "worked tirelessly to raise funds to meet the target for this campaign and are excited to announce that they have achieved their goal where they will be able to fund up to 150 cats for desexing".
The one-off campaign would benefit both Queenstown Cat Rescue and local vets, who also helped find homes for stray cats and kittens.
Queenstown Cat Rescue acknowledged its campaignto "reduce the number of stray cats in the area and endeavour to find abandoned cats and kittens responsible, loving homes" was made possible only through the "professional services provided by the local vets".
Cat owners can register their pets for the freedesexing by calling Ms de Reus on 027 2083725.
She will mail them a desexing voucher, which can be redeemed at specified vets in Queenstown and Cromwell.
She said the offer was being extended to Cromwell because of the number of cats being re-homed in that area.
