"She has her own fortune," he added, thought to be around three million euros ($3.4 million) which she earned with him doing adverts for a German car firm and a Japanese cosmetics brand.
"If anything happens the person who looks after her will not go without," said Lagerfeld, who designed for Chanel, Fendi and his own brand right up to his death aged 85.
Choupette who the designer they called the Kaiser compared to the enigmatic star Greta Garbo is something of a cult figure in the fashion world, with more than 170,000 followers on social media.
She is also the hero of a book, Choupette: The Private Life of a High-Flying Fashion Cat, where she was photographed in arms of supermodel Linda Evangalista and snuggling with model turned actor Laetitia Casta.
Unlike them, the spoiled puss never has has to watch what she eats.
The book includes recipes for her favourite meals prepared by some of the best restaurants in Paris. One typically lavish repast is a mix of king crab, smoked salmon and caviar. And unlike ordinary cats, Choupette eats at a table.
"She is like a human being, only with an extra quality silence," Lagerfeld quipped.