A restored print of Sleigh Bells (1928) will have its world premiere at the BFI in London in next month.
The BFI says the re-discovery of the "long-lost" six-minute film in its archive is a "joyful treat".
Other Oswald films survive but Sleigh Bells has been unseen since its original release.
Oswald the Lucky Rabbit was invented by Walt Disney and Ub Iwerks for Universal in 1927 before they went on to create Mickey Mouse.
The only surviving print of Sleigh Bells was preserved in the BFI National Archive and was "re-discovered" by a researcher browsing its online catalogue.
The restoration work was carried out by Walt Disney Animation Studios and the new print will be shown at BFI Southbank on 12 December as part of a programme of Disney Christmas shorts.
"What a joyful treat to discover a long-lost Walt Disney film in the BFI National Archive and to be able to show Sleigh Bells to a whole new audience 87 years after it was made," said Robin Baker, head curator at the BFI National Archive.
"The restoration of this film will introduce many audiences to Disney's work in the silent period - it clearly demonstrates the vitality and imagination of his animation at a key point in his early career."
Andrew Millstein, president of Walt Disney Animation Studios, which oversaw the restoration, said the Oswald shorts were an important part of Disney history.
"We have been working with film archives and private collectors all around the world to research the missing titles."
A cartoon featuring the first Disney character, Oswald the Lucky Rabbit, is to be screened for the first time in 87 years.