Pooh wakes up one day to find that he is out of honey. While searching for honey, Pooh runs into SpongeBob SquarePants, Patrick Star, Squidward Tentacles, Sandy Cheeks, Eugene Krabs, Alex, Marty, Melman, Gloria, Baloo, and Bagheera and then discovers Eeyore who is even sadder than Pooh because he has lost his tail. SpongeBob, Patrick, Squidward, Sandy, Mr. Krabs, Alex, Marty, Melman, Gloria, Baloo, and Bagheera, Pooh, Tigger, Rabbit, Owl, Kanga, and Roo come to the rescue, and Christopher Robin decides to hold a contest to see who can find Eeyore's tail. The prize for the winner is a fresh pot of honey.
The next day, Pooh goes to visit Christopher Robin and he finds a note that says "Gon Out Bizy Back Soon." Because Pooh is unable to read the note, he asks for Owl's help. Owl's poor reading comprehension skills lead SpongeBob, Alex, Baloo, Skipper, and their friends to believe that Christopher Robin has been abducted by a monster they call the "Backson." SpongeBob, Alex, Baloo, Pooh, and their friends plan to trap the "Backson" in a pit, but they end up getting stuck in their own trap. Piglet attempts to get Pooh and friends out of the trap, but they fail because Piglet's too timid. Pooh uses the words in the storybook to form a ladder, and the animals are able to get out of the trap.
Upon escape, Pooh visits Owl only to find out that Owl was the one that took Eeyore's tail. Owl had been using Eeyore's tail as a pulley for his door. Pooh then goes to Eeyore to tell him about his tail. Christopher Robin is proud of Pooh's kindness and rewards him with a large pot of honey.
Following the credits, it is revealed that the rumored Backson actually exists deep in the woods, but is much friendlier than imagined. He discovers a trail of objects and picks up each one, planning to return them, before falling into the very pit that was made for him. He waits for someone to arrive and help him out.