The Cat Assist Team in Whitchurch will be holding the sale from 10am to 4pm and hope that money raised will help pay towards the rescue's ever-growing veterinary bills.
The charity was formed in 2020 to provide help and support for animals.
Since then its has grown considerably but like many other organisations and charities faces a cost crisis.
The non-profit organisation relies solely on public donations.
Laura Edge, from the Cat Assist Team Whitchurch, said: "The clothes have all been donated by local people and we have loads that will be on sale.
"We have many great items which will be on sale from 50 pence upwards.
"All funds raised will be going towards our ever growing veterinary bills."