"She's such a nightmare," he said. "Her career is over, I can tell you that. Her tour has been a disaster and it couldn't happen to a bigger [expletive]."
"If Madonna had any common sense, she would have made a record like Ray of Light, stayed away from the dance stuff, and just been a great pop singer and made great pop records, which she does brilliantly. But no, she had to prove that she was like . . ." John continued. "And she looks like a [expletive] fairground stripper."
The music legend's feud with Madonna, 53, has been going on for years, and in January his husband, David Furnish, 49, also got involved. After John lost the Golden Globe Award for Best Original Song to Madonna, Furnish publicly slammed her acceptance speech.
"Madonna winning Best Original Song truly shows how these awards have nothing to do with merit. Her acceptance speech was embarrassing in its narcissism," he wrote on his Facebook page. "And her criticism of Gaga shows how desperate she really is."
John also said, during his Sunday interview, that Madonna has "been so horrible to Gaga," who is the godmother of his son, Zachary, 19 months.
"She's amazing," John said of Lady Gaga, 26. "Wherever she is in the world she sends texts saying, 'How is he?' She comes and bathes him and sings to him. She's a good godmother, she really pays attention."
John also revealed that he and his husband are considering having another child together.
"We're thinking about it, very much so," he said. "In the future, I think we're definitely going to have another kid. I don't want him to be an only child. It's bad enough being the child of someone famous and I want someone to have a relationship with him as a brother or sister, without question."