Vicky was aged 19 when her beloved pet disappeared on the day her family was moving from Gildersome to Morley in July 2008.
Vicky, 31, had put Gucci in a room at the new house on Bridge Street in Morley, but he managed to get out and run away.
Vicky and her then 13-year-old sister Tamsin put up dozens of missing cat posters and spent six months searching before giving up hope of ever seeing Gucci again.
The Swainson family had adopted Gucci as a stray kitten and had had him microchipped during the three years he was with them.
On Friday June 19 - almost 12 years after he disappeared - the microchip led to Gucci being reunited with Vicky.
She was shocked and overjoyed to receive a phone call from Abbey House Vets in Morley on Friday June 19 to say they had Gucci.
Gucci had been spotted as a stray on Hardy Street in Morley.
A woman was concerned he looked skinny and unwell and took him to the vets, where the microchip records showed Vicky was his owner.
Vicky, who works as a bank manager in Leeds, said: "It was unbelievable. I just felt so emotional and grateful that someone had taken him into the vets.
"Gucci was happy as well. I picked him up and he was purring away."
Vicky said she had given up hope of seeing Gucci again, adding: "He was really playful and really loving, but we just had to accept that he had gone.
"We didn't know if someone had taken him in or if anything bad had happened to him. It was just awful."
Vicky said she is unable to have Gucci living with her as she has another cat called Larry and didn't want to upset either of the cats.
Gucci is living with Vicky's dad Steve Swinson at his home in Gildersome.
Vicky's eight-year-old niece Amirah Swainson helps care for Gucci.
Vicky said: "It is thanks to microchipping that we have got him back."