The singer claimed that he sounds like a "freak" on the REM cover, which has spent the past two weeks at the top of the UK singles chart.
"My part's rubbish! I sound silly on it," he told Paul Harper on Real Radio.
"I'm so glad it made so much money and so proud to be part of it. Do I think I sound fantastic on it? No!
"I sound odd. Everyone has beautiful voices and I sound like a freak!"
Mika recently revealed that he is planning a US tour to increase his profile Stateside.