The winning bidder, whose name was not reported, bid $500,000 on the item Friday, though commissions added $102,000 to the total, The New York Times reported. Sotheby's had estimated the piano would sell for between $800,000 and $1.2 million.
The piano was one of two used in "Casablanca," and was small, with 58 keys, 30 fewer than a conventional piano.
It was used in a flashback scene at a Paris cafe named "La Belle Aurore." The piano was on camera for 1 minute and 10 seconds, and actor Dooley Wilson, who played Sam in the classic film, mimicked playing it while singing in the film, the Times reported.
Sotheby's last auctioned the piano in 1988 for $155,000, the second-highest price for Hollywood memorabilia at the time, the newspaper said.