One day in a school shortly before Christmas, a magician named Professor Hinkle is hired to perform for the pupils but fails to entertain them, so instead the children go outside and build a snowman, who they name Frosty. However, Professor Hinkle's rabbit and Rabbit's cousin, Hocus Pocus, escapes from the building while wearing his owner's top 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 with a trademark exclamation: "Happy Birthday!"
This delights the students, but after seeing that the hat is actually magic, the agitated Hinkle wants it back. The children refuse to turn it over to him, much to his annoyance. Antagonized by both the children's dislike of his magic performance and the fact that he may not receive his top hat back, Professor Hinkle makes it his main priority to snatch the hat back from Frosty. The children and their snowman gleefully parade through town, shocking passersby with Frosty's anthropomorphism. The children 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.
Karen, a little girl who is especially attached to Frosty, suggests that the group bring him to the North Pole, but they are barred from boarding a train that will take him there due to their lack of tickets. So, Karen and Frosty sneak into the back of a train delivering frozen goods, and off they go. However, Hinkle has also secretly managed to hitch a ride on the train as well in hopes of stealing back his hat; but soon, he accidentally falls off and is knocked cold.
Needing to put as much distance between themselves and Hinkle as possible, Frosty and Karen continue on toward the North Pole, accompanied by Hocus, who has chosen to side with them rather than Hinkle. 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 Claus while Frosty decides to take Karen to a greenhouse for warmth, but Hinkle has since come to and wants the hat back. He blows out Karen's fire and starts to pick a fight with Frosty who dodges and weaves. Being too slow for Hinkle, Frosty sees no other choice but to put Karen on his back and do a belly flop down to the bottom of the hill where a greenhouse lies. Frosty carries Karen inside where she would be warm and safe. However, Hinkle has followed them on foot all the way down the hill to the greenhouse and he locks Frosty and Karen inside.
In the meantime, Hocus manages to bring Santa Claus back to the greenhouse in order to take Karen home. But when they enter, they discover to their horror Karen sobbing over a puddle of water that used to be Frosty, with Frosty's top hat lying nearby. However, Santa Claus revives Frosty by opening the door and letting in a strong wintery wind. Before Karen can put on Frosty's hat, Hinkle pops up and declares that he wants it back. Santa stands up to him and threatens to never deliver another present to Hinkle in all his life if the magician dares to harm Frosty in any way. He also tells him that he'll find a new hat in his stocking on Christmas morning, if he writes his apologies; this causes Hinkle to hurry home and start writing. Afterwards, Santa Claus takes Karen and Frosty on a sleigh ride back to her house. There Frosty and Karen bid each other goodbye and Santa brings Frosty back to the North Pole, keeping his promise that Frosty will be back again someday.
At the end of the program, Hinkle is seen with a new top hat as the title song is sung. Towards the end, the final line is altered with Frosty declaring, "I'll be back on Christmas Day!"
- Ash Ketchum, Misty, Brock, Pikachu, Togepi, Littlefoot, Cera, Ducky, Petrie, Spike, SpongeBob SquarePants, Patrick Star, Bloom, Stella, Flora, Musa, Tecna, Layla, Roxy, Simba, Timon, Pumbaa, Zazu, Terk, Tantor, Baloo, Bagheera, King Louie, the Vultures (Buzzie, Flaps, Ziggy, and Dizzy), Jiminy Cricket, Alex, Marty, Melman, Gloria, the Penguins of Madagascar (Skipper, Kolwalski, Rico, and Private), Genie, Louis, Roger Rabbit, Danny, Sawyer, Rex, Dweeb, Woog, Esla, Rapunzel, Pascal, Flynn Rider, Maximus, Jean-Bob, Speed, Puffin, Chanticleer, Wilbur the Albatross, Owen, Lindsay, Beth, Strawberry Shortcake and her friends, Danny Phantom, Sam Manson, Tucker Foley, Jazz Fenton, Danny, Sawyer, Jean-Bob, Speed, Puffin, Rex, Dweeb, Woog, Elsa, Rapunzel, Pascal, Flynn Rider, Maximus, Chanticleer, Wilbur the Albatross, Bob the Tomato, Larry the Cucumber, Junior Asparagus, Hercules, Megara, Philoctetes, Pegasus, Alice, Pocahontas, Meeko, Flit, Princess Aurora, Prince Phillip, Peter Pan, Tinkerbell, Rosetta, Silvermist, Idressa, Fawn, Oliver, Dodger, Lucky, Cadpig, Rolly, Spot the Chicken, Woody, Buzz Lightyear, Jessie, Tommy Pickles, Chuckie Finster, Simon, Theodore, Brittany, Huckle, Lowly, Woody Woodpecker, Ord, Cassie, Arthur Read Bobby, Cindy, Oliver, Millicent, Greg, Marcia, Peter, Jan, Matthew, Dwayne, Steve, DJ, Stephanie, Michelle, Alex and Nicky, Teddy, Aaron, Denise, Derek, Harry, Rusty, Walter, Casper, Wendy, Kevin McCallister, CeCe, Rocky, Davis, Kelly, Lynn, Pebbles, Bamm-Bamm, Davey, Goliath, Tommy, Dil, Chuckie, Phil, Lil, Kimi, Angelica, Susie, Savannah, Nichole, Z, Doggie Howser, Cake, Miracle, Amy, Benjamin, Alex, Leah, Buffy, Jodi, Little Carbon Soldiers, Vada, Ryan, Noak, Thomas J., Mary Ann, Kaia, Jane, Gina, Teddy Bear, Jack B. Nibble, Little Bo Peep, Baa, Baa Sheep, Mary Quite Contrary, Eep Mouse, Gobo, Red, Mokey, Wembly, Boober, The Doozers, Pablo, Tyron, Tasha, Uniqua, Austin, Flynn, Gunther, Tinka, Leo Little, Carly, Sam, Freddie, Spencer, Kimmy Gibbler, Shirley Temple, Gibby, Daniel Cook, Emily Yeung, Gabriella, Gerald, May, Sid, Alvin, Simon, Theodore, Brittany, Jeanette, Elanor, Millie, Geo, Bot, Caillou, Leo, Sarah, Rosie, Clemintine, Julie, Andre, Jason, Jeffory, Jonus, Emma, Xavier, Billy, Gilbert, The All That Gang, Hannah Montana, Miley Stewart, Lilly, Lola, Oliver Oken, Mike Standley III, Jackson, Robby, Rico Suave, Malcolm, Mallory, Resse, Renee, Dewey, Daisy, Chyna Parks, Olive Doyle, Fletcher Quimby, Lexi Reed, Cameron Parks, Becky O'Shea, Junior Floyd, Jake Berman, Rudy Zolteck, Tad Simpson, Hanon, Murphy, Marcus, Timmy Moore, Nubie, Johnny Vennaro, Briggs, Patterson, Priscilla O'Shea, Debbis O'Shea, Calvin Cambridge, Murph, Ox, Marlon, Reg Stevens, Spanky, Stymie, Froggy, Porky, Buckwheat, Uh-Huh, Waldo, Mary-Anne, Jane Twin #1 & 2, Darla, Alfalfa, Tessie, Sharkboy, Lavagirl, Max, Linus, Marrisa, Nigel, Kyle, Mike, Mark, Jessica, Kimberly, Sarah, Jake, Henry, Lorraine, Cooper, Dylan Schenk, Quinn, Aldo, Ethan, Marrisa, Bina, Ely, Otter, Lau, Mick, Christina Beardsley, Harry Beardsley, Michael Beardsley, Kelly Beardsley, Phoebe, Naoko North, Joni North, Jimi North, Paisley Houndstooth, Darryl Parks, Roxanne Parks, Becky Murtaugh, Kenneth Murtaugh, Elliott Murtaugh, Daniel Murtaugh, Lisa Murtaugh, Robin Murtaugh, Bindi, Rosie, Matilda, Lavender, Bruce, Arena, Ben Hilton, Jamie, Max, Becca, Nicky, Jeannie, The Flash/Tony, Crispin, Dylan, Duncan, Sean, Tony's Brother, Juel, Erin, Twist, Kiki, Marina, Shout, Dragon, Alligator, Ostrich, Beaver, Cat, Mailmouse, Dennis Mitchell, Joey, Gina, Margaret, Gunther, Hector, Jessica, Lisa, Keith Watson, Marcus Barnes, Susan Evers, Sharon McKendrick, Sharon Ferris, Susan Carey, Hallie Parker, Annie James, Kady Jay Kyle, Franklin Aloyisious Mumford & Friends, Peter Pan, Wendy Darling, John Darling, Michael Darling, Slightly, Nibs, Curly, Twin #1 & 2, Tiger Lily, Tootles, Messenger Boy, Young Wendy, Young Skeeter, Madeline, Aggie, Victoria, Chantel, Lucinda, Serena, Sylvette, Veronica, Lolo, Julie, Beatrice, Taylor, Jackson C., Madeline Riggs, Morgan Riggs, Derek Venturi, Casey MacDonald, Richelle, Reese Ambler, Rydell, Becky, Kimberly, Dylan and their friends, Lizzie MacDonald, Edwin Venturi, Marti Venturi, Vicki, Truman French, Tina Kathleen Miller, Ramona, Beezus, Cory Baxter, Newton Livingston III, Meena Paroom, Sophia Martinez, Haley, Nat Wolff, Alex Wolff, Thomas, David, Qaasim, Cooper Pillot, Jesse Draper, Tanner Boyle, Ahmad Abdul Rahim, Amanda Wurlitzer, Engelberg, Jose Agilar, Regi Tower, Miguel Agilar, Kelly Leak, Ogilvie, John, Peter, Quinn, Jimmy Feldman, Rudi Stein, Tony Thompson, Rudolph Sackville-Bagg, Anna Sackville-Bagg, Gregory Sackville-Bagg, Timmy Lupus, Eric, Charlie, Nicole, Dena, Jared, Riley, Stacy, Kenny, Lauren, Anthony, Robin, Ana, Haylie, Ryan, Connie, Gloria, Flip, Devyn, Mickey, Richie, Annie, Jamal Jenkins, Lenni Frazier, Alex Fernández, Gaby Fernández, Tina Nguyen, Rob Baker, Héctor Carrero, Casey Austin, CeCe Jenkins, Greg, DJ, Malcolm, Daniel Cook, Stan Marsh, Kyle Broflovski, Eric Cartman, Kenny McCormick, Alex, Marty, Melman, Gloria, King Julien, Maurice, Mort, Terk, Tantor, Taran, Princess Eilonwy, Fflewddur Fflam, Gurgi, Orddu, Orgoch, and Orwen, Aladdin, Princess Jasmine, Abu, Genie, Iago, Brer Rabbit, Jesse Greenwood, Elvis, Randolph Johnson, Nadine, Fievel Mousekewitz, Tiger, Tony Toponi, Tanya Mousekewitz, Yasha Mousekewitz, Papa Mousekewitz, Mama Mouskewitz, Ariel, Flounder, Sebastian, The Goonies (Mikey Walsh, Brand Walsh, Mouth Devereaux, Data Wang, Chunk Cohen, Andy Carmichael, Stef Steinbrenner, and Sloth Fratelli), Baloo, Bagheera, King Louie, Manny, Sid, Diego, Charlie Barkin, Itchy Itchiford, Sasha, Fu Dog, Kenai, Koda, Rutt and Tuke, Roger Rabbit, Mickey Mouse, Donald Duck, Goofy, Scrooge McDuck, Huey, Dewey and Louie, Webby, Bugs Bunny, Daffy Duck, Resse, Ryndall, Robin Hood, Little John, Wilbur the Albatross, Mrs. Brisby, Jeremy the Crow, Jean-Bob, Speed, Puffin, Ttark, Woody Woodpecker, Slimer, Stay Puft, Toaster, Lampy, Radio, Blanky, Kirby, Jimmy Neutron, Carl Wheezer, Sheen, Cindy Vortex, Libby, The Muppets (Kermit the Frog, Fozzie Bear, The Great Gonzo, Miss Piggy, Rowlf the Dog, Scooter, The Eletric Mayhem, Rizzo the Rat, and Walter), Fred Flintstone, Wilma Flintstone, Pebbles Flintstone, Dino, Barney Rubble, Betty Rubble, Bamm-Bamm Rubble, George Jetson, Jane Jetson, Judy Jetson, Elroy Jetson, Astro, Rosie the Robot, Mr. Spacely, Yogi Bear, Boo-Boo Bear, Snagglepuss, Huckleberry Hound, Quick Draw McGraw, Augie Doggie and Doggie Daddy, Wally Gator, Magilla Gorilla, Top Cat, Peter Potamus, Scooby-Doo, Shaggy Rogers, Fred Jones, Daphne Blake, Velma Dinkley, Scrappy-Doo, Rex, Woog, Elsa, Dweeb, Jack Skellington, Kids World's Adventures Team and the rest of the characters are back will guest star in this film.