The small red chalk sketch is thought to date to about 1511-1512 when Michelangelo was preparing to work on the second half of his painting of the Sistine ceiling, which included the Libyan Sibyl.
The anonymous owner, who is based on the US West Coast, told Christie’s he had inherited the drawing from his grandmother.
The man said it had been passed down through the family in Europe since the late 1700s.
A specialist in Christie’s Old Master Drawings Department, Giada Damen, used infrared reflectography, which revealed drawings on the back of the sheet which also resembled Michelangelo’s work.
Damen then took the foot and set it next to the Michelangelo drawing at the Metropolitan Museum, concluding the sketch was an original.
Famous pieces of art selling for millions is not unusual:
Also in November 2025, a surrealist painting by famed Mexican artist Frida Kahlo was sold for $54.7m, shattering the auction record for an artwork by a woman.