The Chanel designer is a big fan of the party planner and thinks she is much more attractive than her daughters Pippa - who he recently slammed, saying he ''didn't like'' her face - and Britain's Duchess Catherine.
He told Grazia magazine: ''I think Carole is very sexy. I think the mother is sexier than the daughters. There is something full of life about her. For a woman who must be 50 or so, I think she's great. Full of energy.''
Despite his criticisms of Pippa, Karl insists he was misunderstood.
He said: ''I didn't mean that. I only meant I don't think her make-up is right. She has a roundish face and round eyes and she should pick another make-up for the eyes.
''Her sister's more beautiful. Kate can try anything. For make-up she has no limits.''
Karl recently praised the duchess - who was known as Kate Middleton before she married Prince William - as a ''romantic beauty'', but slammed Pippa for her ''struggles'' to look good.
He said: ''Kate Middleton has a nice silhouette and she is the right girl for that boy. I like that kind of woman, I like romantic beauties.
''On the other hand, her sister struggles. I don't like the sister's face. She should only show her back.''