The instrument, a 1962 Gibson J-160E, was one of a pair of identical acoustic guitars bought by Lennon and bandmate George Harrison in September 1962, according to Los Angeles-based Julien's Auctions, which promoted it as "the most important Beatle guitar ever to hit the auction block."
In a news release, the auction house said the guitar went missing following a Beatles concert in London in December 1963, and its location was unknown for more than 50 years. Lennon subsequently replaced it with a 1964 model.
The instrument was rediscovered last year when a man noticed close similarities between an acoustic guitar he owned and one featured in a magazine story about George Harrison's guitar collection, according to the release. A New York-based expert was able to confirm that the instrument was Lennon's missing acoustic.
In the 15-month period the instrument was in Lennon's possession, it was used on a number of the band's early hits, including "She Loves You," "Please, Please, Me," "All My Loving" and "From Me to You," the auction house said.
The day after Lennon and Harrison received their guitars, purchased in Liverpool for £161 each, they traveled to a London studio to record "P.S. I Love You" and "Love Me Do," the auction house said. Lennon can be seen playing the instrument in the 1963 video for "I Want to Hold Your Hand."
The auction house had earlier estimated the instrument would sell for $600,000 - $800,000.
The drum head the Beatles used in their breakthrough U.S. performance on "The Ed Sullivan Show" in 1964 was also sold Saturday for $2,050,000, the auction house tweeted.