One day in a school shortly before Christmas, an inept magician named Professor Hinkle is hired to perform for the children but fails to entertain them, so instead the children (along with Bloom, Stella, Flora, Musa, Tecna, Layla, Lumiere, Cogsworth, Mrs. Potts, Chip, Scuttle, Simba, Nala, Timon, Pumbaa, Alex, Marty, Melman, Gloria, Skipper, Kolwalski, Rico, Pirvate, King Julien, Maurice, Mort, Terk, Tantor, Genie, Roger Rabbit, SpongeBob SquarePants, and Patrick Star) go outside and build a snowman, whom they name Frosty (suggested names included Harold, Bruce, Christopher Columbus and Oatmeal). However, Hinkle's rabbit Hocus Pocus, escapes from the building while wearing his hat, which the children decide to put on top of Frosty's head. To their surprise, the magic of the hat causes Frosty to come to life.
This delights the students and the heroes, but after seeing that the hat is actually magic, the agitated Hinkle wants it back. The children and the heroes refuse to turn it over to him, much to his annoyance. After he leaves, Hocus returns the hat to the children and Bloom, Simba, Alex, SpongeBob, and their friends, thus bringing Frosty to life for the second time. The children and Bloom and the others are very happy with their new friend, but the temperature is rising and Frosty must leave for somewhere that is colder or else he will melt, to which Frosty explains that the only place he won't melt is the North Pole. They parade through town to the train station, shocking passersby with Frosty's anthropomorphism and even having a sudden stopping with a policeman. When they get to the station however, they are barred from boarding a train that will take them there due to their lack of money to buy tickets. So, Karen, Frosty, Hocus, and Bloom, Simba, Alex, SpongeBob, and their friends sneak into the back of a train headed north. However, Hinkle (now whom Dr. Facilier works for) sneaks aboard, determining to get the hat back.
Needing to put as much distance between themselves and Hinkle and Facilier as possible, Frosty, Karen, and the others continue on toward the North Pole, accompanied by Hocus, who has chosen to side with them rather than Hinkle and Facilier. While Frosty is safe from melting, Karen is freezing and Hocus, seeing her predicament, gathers with a group of woodland creatures to build a fire for her. Frosty knows that it is best if Karen is brought home, and he and Hocus decide to enlist the help of Santa Claus to transport her there.
Hocus leaves to search for Santa, but Hinkle and Facilier comes back to steal the hat back. Being too slow for Hinkle and Facilier, Frosty, Karen, and the others race down the hill to a small greenhouse, used to grow poinsettias. Frosty, Bloom, Simba, Alex, SpongeBob, and their friends carries Karen inside where she will be warm and safe. However, Hinkle and Facilier have followed them on foot all the way down the hill to the greenhouse and locks everyone inside.
Hocus brings Santa to the greenhouse, only to find Karen and the others crying over a melted Frosty. Santa explains to them that Frosty is made of Christmas snow and can never melt away. To cheer them up, he opens the door to the greenhouse, reviving Frosty. However, Hinkle arrives, once again claiming that the hat is still his. Santa warns him that if he swipes the hat, he will never get another Christmas present from him for the rest of his life. Hinkle begs for another chance, and Santa tells him that if he starts acting nicer and writes a formal apology, Santa will maybe reconsider and possibly give Hinkle a new hat for Christmas, to which an overjoyed Hinkle runs home to write his apologies, in the hopes of getting that new hat. Just as Dr. Facilier was about to capture Bloom and her friends, Patrick Star smashed the voodoo talisman, causing the witch doctor to be dragged to the underworld by his Friends on the Other Side yet again. Afterwards, Santa takes Karen on a sleigh ride home and brings Frosty back to the North Pole, keeping his promise to her that Frosty will return every year when another Christmas snowfall comes around. As Bloom and her friends are about to end their adventure, they ask Frosty if join them. He agrees after the Alfea students casted a magic spell on him to prevent him from melting.
As the end credits roll, Frosty leads the children, the narrator, and the rest of the town on another parade through town, and Hinkle is seen with a new top hat as the title song is sung. At the end of the parade, Frosty climbs in the back of Santa's sleigh and the final line is altered with him saying, "I'll be back on Christmas Day!"
- Simba, Nala, Timon, Pumbaa, Terk, Tantor, Alex, Marty, Melman, Gloria, The Penguins of Madagascar (Skipper, Kolwalski, Rico, and Private), King Julien, Maurice, Mort, Genie, Roger Rabbit, SpongeBob SquarePants,Patrick Star, and Dr. Facilier will guest star in this film.
- Dr. Facilier will work for Professor Hinkle in this film.
- Frosty the Snowman will join the Alfea Adventure Crew at the end of this film after Bloom and her friends give him a magic flurry that would prevent him from melting.
- This is the first (and so far, only) Winx Club crossover with a Rankin Bass Christmas classic.