'That Sounds Good To Me', which will be sung by Josh Dubovie, 19, in Oslo tonight, was penned for the competition by the former Pop Idol judge.
Bookies have placed record odds against the song's chances of winning, though Dubovie has said that, regardless of criticism, he will perform with a smile on his face.
Responding to Dr Fox's judgement of the tune as "average", Waterman, 63, told The Sun: "When did he last write a f**king hit song? He can't even speak English, let alone write a hit song. Dr Fox? He is not even a real doctor. He doesn't know anything."
The hitmaker went on to say that Eurovision has become "too arty", adding: "It's become waylaid by people trying to be serious artists. Hang on a minute, we're here to party! This isn't showbusiness, it's a song contest."