All proceeds from the auction of the Susan Sommer-Luarca's portrait, in acrylic on canvas, will benefit the Barbaro Memorial Fund.
The winning bidder was named as John Koenig, of Franklin Square, New York, who believes Barbaro was the greatest horse since Secretariat and Ruffian.
Money in the Barbaro Memorial Fund is being used for equine health and safety research.
Barbaro suffered a shattered hind leg near the start of last year's Preakness Stakes. While ground-breaking treatment helped heal the fracture, he was euthanized nearly nine months later when laminitic complications became too severe.