The Swan Princess III: The Mystery of the Enchanted Treasure, alternatively titled The Swan Princess: The Mystery of the Enchanted Kingdom, is a 1998 American animated direct-to-video musical adventure film and the third installment in The Swan Princess franchise. It was directed again by Richard Rich, and features the voices of Michelle Nicastro and Brian Nissen as Odette and Derek. This film follows Derek and Odette having to deal with Zelda, a sorceress who is seeking the Forbidden Arts and wishes to use it to destroy their happiness.

This sequel features the returning voices of Nicastro and Steve Vinovich from the first film, which would be the last time, with the former's death in 2010, with all the other characters being re-cast. The overseas production was handled by Hanho Heung-Up, a South Korean animation studio that provided cel painting service for the original film, and also animated the first direct-to-video sequel, The Swan Princess: Escape from Castle Mountain. It was the last film in the series to use traditional 2D animation. The film was seemingly the end of the series, until 2012, when it was followed by another direct-to-DVD sequel: The Swan Princess: Christmas, which consists of 3D computer animation for the first time.