The Washington Post said the piece of cinematic history was sold by the auction house Nate D. Sanders
to an anonymous buyer.
Welles wrote, directed and starred in the 1941 movie, for which he won the Best Screenplay Academy Award.
He died in 1985 at age 70. His Oscar was believed to have been lost for decades before it landed on the auction block, the Post said.
Hollywood's Academy of Motion Picture Arts & Sciences banned winners and their heirs from selling Oscars beginning in 1950. Welles' statuette was presented to him before the rule went into effect.