The Swan Princess Christmas is the fourth sequel to The Swan Princess series.
Princess Odette and Prince Derek are on their way to Queen Uberta's castle to celebrate their very first Christmas together as beloved husband and wife. Unbeknownst to them, however, the exceedingly strong and dangerous enchanter Rothbart has put in a motion a plan to return from the dead, enlisting a black cat named Number 9 to help by promising him nine extra lives. Number 9 succeeds in luring Derek to the cellar of Uberta's castle where he opens a chest with the initial R on it. At first there is nothing inside, but once Derek leaves, Rothbart emerges from the chest as a ghost. From here, Rothbart moves to the next portion his plan, which is to destroy the Christmas spirit of the kingdom (the only thing more powerful than the Forbidden Arts) which will give him the power to be fully revived in bodily form of solid flesh and blood. Rothbart is able to cast minor spells of dark magic that cause people to fight and abhor the Christmas spirit. He does this to Queen Uberta and Lord Rogers, and later to the villagers until almost the entire village is in disharmony.
Derek and Odette learn of Rothbart's return as a ghostly spirit when wind chimes playing "Far Longer than Forever" make him visible and hold him immobile. They set up chimes all around the castle, but Rothbart eventually re-enlists the help of Bridget (his hag henchwoman from the first film who had turned good) and she helps remove the wind chimes for him.
As part of the Christmas festivities, Uberta and Rogers are staging musical performances, but because of Rothbart's spell have become aggressive and competitive with each other. Odette, who has been invited to stage her own song, invites orphans to perform "Christmas is the Reason" which momentarily weakens Rothbart's power over Uberta and Rogers. Odette follows up on this by inviting Uberta and Rogers to give gifts and food to the poor. This time the good will breaks the spell on the whole kingdom, and Rothbart is rendered severely weakened nearly powerless.
Rothbart's last chance to ruin Christmas' magical and mystical spirit is to sabotage the royal Christmas tree. He sends Number 9 to steal one of the Christmas lights, and Rothbart casts a dark spell on it that will destroy the tree. Derek learns of this plan thanks to Bridget, who has double-crossed Rothbart and traps him inside a giant chime.
Derek rushes back to the Christmas Eve party to stop the tree from being lit, but they are too late. The enchanted light bulb bursts the tree and its ornaments into flames. Rothbart becomes fully restored to his physical body, takes Uberta's crown, and kidnaps Odette where he takes her back to Swan Lake.
At Swan Lake, Rothbart once again turns Odette into a white swan and traps her inside a cage made of roots. He then casts a spell on the moonlight, so that when it touches Odette's wings, she will turn into a golden swan-shaped Christmas ornament forever. Derek arrives to rescue Odette and Rothbart has assumed the form of the Great Animal again to fight Derek. At first Derek is overpowered, but then Odette starts singing "The Season of Love," which slowly weakens Rothbart until he eventually bursts into flames. With Rothbart defeated for a second time, Odette changes back into a human. Derek dies in her arms due to his injuries, but when a tearful and deeply distraught Odette sings again, the great spirit of Christmas magically returns him to life and restores the royal Christmas Tree. At the Christmas Eve party, the kingdom puts up a new Christmas ornament on the tree, honoring Derek and Odette.
- This is the first Swan Princess movie to be computer-animated and rated PG.