The 46-year-old journalist - who now fronts CNN's Piers Morgan Tonight - says he hates Kate, 38, and the supermodel despises him in equal measure.
He said: "She doesn't like me, I don't like her.
"Kate Moss is utterly horrific. If people actually knew what she was like they would never, ever be interested in her again.
"She's just a real, spoilt little madam from Croydon. There's nothing wrong with Croydon - I was brought up near Croydon. But she's just a vile little creature."
Moving on to the topic of Madonna, Piers - who has banned the Hung Up singer from his chat show - took aim at her toned physique.
He told the Daily Mirror newspaper: "Those arms are just terrifying. It's like watching Conan the Barbarian. She's looking even more barbaric than ever at the moment, utterly grotesque.
"When I got the CNN job I banned her from the show, permanently. She responded by saying she'd never heard of me, but we both know she's lying."
But he insists he doesn't hate all of Hollywood and even has kind words to spare for actresses Gwyneth Paltrow and Cameron Diaz.
He said: "Gwyneth is a dark horse, much more fun than you might think.
"When I asked her about her reputation, she told me she was a demure, lovely, sweet, innocent little lady ... except in the bedroom.
"I had a good laugh with Cameron at Vanity Fair [Oscars party]. She's a really cool girl, good fun. She wants to come on my show, but only when she's got something intelligent to say."
- BANG! Showbiz