In the Hundred Acre Wood, SpongeBob SquarePants (Tom Kenny), Patrick Star (Bill Fagerbakke), Squidward Tentacles (Rodger Bumpass), Sandy Cheeks (Carolyn Lawrence), Eugene Krabs (Clancy Brown), Baloo (John Goodman), Bagheera, King Louie (Jim Cummings), Eeyore (Peter Cullen), Rabbit (Ken Sansom), Tigger, andWinnie the Pooh (Jim Cummings) are working on a plan to extract honey from a beehive. The plan involves getting the bees to convey to a new hive by convincing them that Eeyore is a bee. Piglet (John Fiedler) comes up to them during the attempt, but is effectively told that he is too small to help. The plan goes awry when the bees do not fall for it, but Piglet manages to divert the bees into the new hive using a funnel and then seals the hive shut, trapping the bees.
However, no one has realized what Piglet had done to help out with the plan, having Piglet feeling uncared for; Piglet sadly wanders away. Eventually, SpongeBob, Patrick, Squidward, Sandy, Mr. Krabs, Baloo, Bagheera, King Louie, Pooh, Rabbit, and Tigger notice that Piglet is missing, assuming that he has been scared off by the bees, and decide to find him. They are joined by Roo (Nikita Hopkins), and together the five friends search for Piglet. The search party is aided by Piglets' scrapbook, in which he has drawn pictures of the adventures that he has shared with his friends. The characters use the pictures to tell the stories depicted therein.
One of the stories told is the expedition to find the North Pole, where Piglet uses a long stick to save Roo (who has fallen in the river). His heroism is overlooked when he gives the stick to Pooh and tries to catch Roo, who has been catapulted into the air during the rescue attempt. Christopher Robin (Tom Wheatley) arrives as Roo is caught by Kanga (Kath Soucie) and then credits Pooh with finding the North Pole (the stick he is holding in his paws). Back in the present, the friends regret not sharing the praise with Piglet.
A second story told is the building of The House at Pooh Corner. Here Piglet comes up with the idea to build Eeyore a house and he, SpongeBob, Patrick, Squidward, Sandy, and Pooh are joined by Tigger to build it. SpongeBob, Patrick, Squidward, Sandy, Mr. Krabs, Baloo, Bagheera, King Louie, Tigger, and Pooh do most of the work, whilst Piglet, unintentionally, gets in the way. The final house, however, is a disaster, but SpongeBob, Patrick, Squidward, Sandy, Tigger, and Pooh go off to tell Eeyore about the house. Unfortunately, the house is being held together by Piglet, who eventually loses his grip and the house collapses. SpongeBob, Patrick, Squidward, Sandy, Mr. Krabs, Baloo, Bagheera, King Louie, Tigger, and Pooh go to inform Eeyore of the bad news, but Piglet arrives to tell them all that the house is fine. It is revealed that he rebuilt the house himself, but the location remains as Pooh Corner, since Pooh "would call it 'Pooh and Piglet Corner', if 'Pooh Corner' didn't sound better, which it does, being smaller and more like a corner".
Back in the present, an argument between Rabbit and Tigger ends with the scrapbook falling apart and then falling into the river. Without their guide, the friends return to Piglets house and, after a time, start to draw new pictures of Piglet and his adventures, some of which are new. Then, the friends again resolve to find their missing Piglet and go back out to find him. They come across several pictures from the scrapbook, which have floated downstream and then find the books bindings, suspended on a broken hollow old log, overhanging a raging waterfall. Pooh goes to retrieve it, but falls into a hole in the log. The others try to reach him, but the rescue attempt is just too short. Just as they ask who can help, Piglet arrives and attempts to help haul Pooh to safety, just as the log begins to collapse.
SpongeBob, Patrick, Squidward, Sandy, Mr. Krabs, Baloo, Bagheera, King Louie, Eeyore, Rabbit, Roo, and Tigger now stand by the edge of the ravine, next to the waterfall, but the log inside which Pooh and Piglet were trapped has fallen far into the waters below. The survivors begin to cry but are soon joined by a sad-looking Pooh and Piglet, who have managed to escape. Happy, the friends take Piglet to show him their new drawings, including a large one of Piglet dressed as a knight in shining armor. The next day they hold a party, but Pooh interrupts, taking Piglet to Eeyores' house, where he has changed the sign to read "Pooh and Piglet Corner"; "the least [they] could do for a little Piglet, who has done such big things!".
- Alex, Marty, Melman, Gloria, Baloo, Sebastian, Bagheera, King Louie, Fu Dog, Rutt and Tuke, and Roger Rabbit guest star in this film, although Roger Rabbit will be absent from the first flashback of this film, due to Kanga and Roo meeting Roger Rabbit in Pooh's Adventures of Who Framed Roger Rabbit.
- This is an NTSC film with NTSC bits from The SpongeBob SquarePants Movie, the Madagascar films, The Little Mermaid films, The Jungle Book 1 and 2, Brother Bear 1 and 2, and Who Framed Roger Rabbit.