But the fashion maestro has revealed that he finds beauty in Cara's imperfections. "She is not a standout beauty," he said in an interview with The Guardian.
"Was it Bacon who said, 'There is not beauty without some strangeness in the proportions'?"
Cara and Karl walked out together for the finale of his supermarket-themed Chanel show in Paris last month.
The set was fully stocked with Chanel-branded food – notable items included haute Ketchup, eau de Chanel and Jambon Cambon, named after the location of Chanel's original store.
But the Grand Palais descended into chaos when it was time for show-goers to leave, with a rush for Chanel-branded souvenirs.
Asked about the scrum, it was clear Karl was not amused. "I saw it on film later and the bodyguards were removing things from people's bag," he said.
"I did not expect that of people who normally come to my shows."
The groceries were intended to go to homeless shelters, while the empty packaging was to create Chanel window displays.
Karl opened up about his famous cat, Choupette, revealing that he is sent picture updates of her activities from the cat's maid every hour.
"Everything is controlled by her," he said. "She wakes me up at 7am because she wants me to bring her fresh croquettes – she won't touch food from the night before, she gets offers for food commercials but it is out of the question. She is a kept woman."