The 45-pound, 12-inch-tall prop was auctioned off on Monday for $4,085,000, according to Bonhams auction house. That price includes Bonham's premium.
The black statuette is one of two known cast lead figurines made for John Huston's screen version of the film but the only one confirmed by Warner Bros. archives as having appeared in it, said Bonhams.
The winning bid came over the phone on Monday.
A Warner Bros. inventory number is etched into the base of the statuette. The base also bears the name of the film, which starred Humphrey Bogart as private eye Sam Spade.
Bonhams said the figure has a bent right tail feather, damage incurred during filming. Actress Lee Patrick, who played Spade's secretary, Effie, dropped it while handing it to Bogart.
The unidentified owner of the figurine bought it privately in the 1980s. It has been exhibited at the Warner Bros. Studio Museum, the Pompidou Centre in Paris and the Museum of Modern Art in New York.
It was offered in a sale of other classic movie memorabilia.
The Associated Press contributed to this report.