The 43 year-old star was arrested last October when witnesses reported seeing the star slumped over the steering wheel of his car.
Michael, whose real name is George Panayitou, explained that his actions were the result of "tiredness and prescribed drugs".
Michael had taken a combination of anti-depressants, GHB and cannabis. The singer, who was found guilty of driving while unfit due to drugs, will be sentenced on June 8.