The 29-year-old world number one reached the landmark figure by making the French Open quarter-finals on Thursday.
"Believe it or not, I never thought of prize money being one of the sources of my motivation and inspiration to play tennis," said Djokovic, after reaching the semi-finals on Friday to guarantee at least another $500,000.
"Of course the money helps me have a certain standard of life and lifestyle. But that's all. It never was and is never going to be the driving force in my life and in my career."