Guinness World Records and charity Cats Protection have recognised Flossie, born in 1995, as the world's oldest living cat.
Flossie was signed over to volunteers in Kent aged 26 after her owner was unable to support her.
But her fortunes changed after she was given a new home with experienced senior cat carer and executive assistant Vicki Green, who lives in Orpington in southeast London.
Remarkably Vicki is the same age as her new pet, who turns 27 in a few weeks.
Despite being deaf and having failing eyesight, Flossie is described by Miss Green as "affectionate, playful and sweet".
"I knew from the start that Flossie was a special cat, but I didn't imagine I'd be sharing my home with a Guinness World Records title holder," Miss Green said.
"She sometimes misses her litter box or needs help grooming herself, but I can help with all of that. We're in this together.
"She never turns her nose up at the chance of a good meal, except when she's snuggled on her favourite yellow blanket."
After being looked after by two workers near a Merseyside hospital back in 1995, Flossie was with her first owner for 10 years until they died.
Taken in by the owner's sister, Flossie stayed there for another 14 years until that owner also died.
Flossie was with the woman's son for three years until his situation forced him to take her to the Tunbridge Wells, Crowborough and district branch of Cats Protection.
Naomi Rosling, co-ordinator at the branch, said: "We were flabbergasted when vet records showed Flossie to be nearly 27 years old.
"She's the oldest cat I've ever met, at least 120 in human years. If I'm in such good shape when I'm her age, with someone who does what's best for me when I need it most, I shall be a very happy lady."
According to Omni Calculator, 27 human years is the equivalent to 124 cat years.
However, she still has a way to go to beat the record for the oldest cat ever - Creme Puff - who lived to an impressive 38 years and three days with her owner Jake Perry in Austin, Texas.