The feline, affectionately dubbed Hobo, was rescued from the derelict building in Bracknell town centre.
He was spotted by a member of the public who took a photo of him and sent it to the Cats Protection.
Welfare officers from the charity contacted Comer Homes, owner of the building, which let them in to rescue the forlorn feline, who had been living among debris and broken glass.
It is believed Hobo, who is estimated to be two to three years old, survived on a diet of pigeons after catching the birds.
It is thought to have been living in the tower block – due to be demolished by November and new apartments built on the site – for more than a year.
Cats Protection believes he might have been imprisoned for that long after the owners confirmed they heard rumours of a cat seen in the windows dating back to spring last year.
As the only way in to the building is through a heavy iron door with a large padlock, Cats Protection believes that Hobo might have been taken into the building by a tramp and then abandoned.
Alison Stratford, welfare officer for the charity, said: “He squints when he looks up which may be because he is unused to bright daylight.
“He has an old wound on one pad most probably caused by broken glass.”
Hobo’s feet are also exceptionally soft from living in the carpeted building for so long.
Lynne Pothecary, publicity officer for the Bracknell and Wokingham Districts branch of the Cats Protection, said: “He was immediately taken to Moor
Cottage Vets for a check-up.
“He appeared to be a healthy, neutered male tabby and white cat. His teeth are in excellent condition due to his ‘raw’ diet.”
Hobo is now in the care of a fosterer after being rescued two weeks ago and she has reported he devours everything in sight, and she has had to start feeding him dried foods. He is not microchipped and Cats Protection is appealing for anyone who may know his owners. It is searching lost cat databases but if no owner can be found they would seek a permanent home for Hobo. If you know his owners, or are potentially interested in giving him a home, please call Cats Protection on 0845 371 4212.