The promoter for the British singer and songwriter's two concerts in the Russian capital, to take place at the Olimpiisky stadium July 5 and Luzhniki the next day, said money would be donated to the foundation Podari Zhizn, or Give a New Life.
Alexander Mironenko said the pop star had also given $25,000 to pay for treatment for a three-year Russian boy suffering from leukemia earlier.
Michael, 43, received $3 million for an hour-long concert for a Russian billionaire on this New Year's Eve and prior to the Moscow event, he gave a free concert for nurses in London.
Dina Korzun, an actress and charity founder, praised the singer's generosity, which she said could encourage other people to follow suit. She said bone marrow transplantations in Russia were funded by private donations.
"We did not have to wander cap in hand," Korzun said.
George Michael, whose mother died of cancer in 1997, also reserved 100 free tickets for medical personnel from children's oncological hospitals in Moscow.
Initially, one concert was planned in Moscow for July 5, but an additional event was arranged due to high demand for tickets.