The portrait was painted with household gloss.
Artist Damien Hirst
The money raised from the sale of Beautiful Beautiful George Michael Love Painting will go to HIV/Aids charity The Goss-Michael Foundation.
The charity was founded by Michael and his former partner Kenny Goss.
Goss posted an image of the artwork on Instagram, writing: “Amazing result of $580,000 (around £461,011).”
He described Damien Hirst as a “superstar”, adding: “Thank you Damien!”
The canvas went under the hammer in Dallas, Texas, at the MTV Re:define charity gala.
Michael, who enjoyed a lucrative pop career as one half of duo Wham before embarking on a successful solo career, died on Christmas Day last year at the age of 53.