Toaster's Big Movie is a film of SpongeBob and Nicktoons: The Series, starring the lovable The Brave Little Toaster.
When Toaster is missing because he is "too small" to help his friends, SpongeBob, Jimmy, Timmy, B.O.B., XJ-4, Lampy, Radio, Blanky, Kirby, WALL-E and EVE discovers Toaster's memory scrapbook that they remembers their adventures and find him.
In Nick-Ville, WALL-E (Ben Brutt), EVE (Elissa Knight), B.O.B. (Seth Rogen), Timmy (Tara Strong), Jimmy (Debi Derryberry) and SpongeBob (Tom Kenny) are working on a plan to extract jelly from a jellyfish hive. The plan involves getting the jellyfishes to convey to a new hive by convincing them that WALL-E is a bee. Toaster (Deanna Oliver) comes up to them during the attempt, but is effectively told that he is too small to help. The plan goes awry when the jellyfishes do not fall for it, but Toaster manages to divert the bees into the new hive using a funnel and then seals the hive shut, trapping the jellyfishes.
However, no one has realized what Toaster had done to help out with the plan, having Toaster feeling uncared for; Toaster sadly wanders away. Eventually, SpongeBob, Jimmy, Timmy, B.O.B., WALL-E, and EVE notice that Toaster is missing, assuming that he has been scared off by the jellyfishes, and decide to find him. They are joined by XJ-3, Lampy (Timothy Stack), Radio (Roger Kabler), Blanky (Eric Lloyd), Kirby (Thurl Ravenscroft) and XJ-4 (Kath Soucie), and together the twelve friends search for Toaster. The search party is aided by Toaster's 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 Toaster uses a long stick to save XJ-3 (who has fallen in the river). His heroism is overlooked when he gives the stick to SpongeBob and tries to catch XJ-3, who has been catapulted into the air during the rescue attempt. Ted (Zachary Gordon) arrives as XJ-3 is caught by XJ-4 and then credits SpongeBob with finding the North Pole (the stick he is holding in his hands). Back in the present, the friends regret not sharing the praise with Toaster.
A second story told is the building of The House at SpongeBob Corner. Here Toaster comes up with the idea to build WALL-E and EVE a new house and he and SpongeBob are joined by Jimmy, Timmy and B.O.B. to build it. SpongeBob, Jimmy, Timmy and B.O.B. do most of the work, whilst Toaster, unintentionally, gets in the way. The final house, however, is a disaster, but SpongeBob, Jimmy, Timmy and B.O.B. go off to tell WALL-E and EVE about the new house. Unfortunately, the house is being held together by Toaster, who eventually loses his grip and the house collapses. SpongeBob, Jimmy, Timmy and B.O.B. go to inform WALL-E and EVE of the bad news, but Toaster arrives to tell them all that the house is fine. It is revealed that he rebuilt the house himself, but the location remains as SpongeBob Corner, since SpongeBob "would call it 'SpongeBob and Toaster Corner', if 'SpongeBob Corner' didn't sound better, which it does, being smaller and more like a corner".
Back in the present, an argument between EVE and Jimmy ends with the scrapbook falling apart and then falling into the river. Without their guide, the friends return to Toaster's house and, after a time, start to draw new pictures of Toaster and his adventures, some of which are new. Then, the friends again resolve to find their missing Toaster 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. SpongeBob 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, Toaster arrives and attempts to help haul SpongeBob to safety, just as the log begins to collapse.
WALL-E, EVE, Jimmy, Timmy, B.O.B., XJ-4, Lampy, Radio, Blanky, Kirby and XJ-3 now stand by the edge of the ravine, next to the waterfall, but the log inside which SpongeBob and Toaster were trapped has fallen far into the waters below. The survivors begin to cry but are soon joined by a sad-looking SpongeBob and Toaster, who have managed to escape. Happy, the friends take Toaster to show him their new drawings, including a large one of Toaster dressed as a knight in shining armor. The next day they hold a party, but SpongeBob interrupts, taking Toaster to WALL-E and EVE's house, where he has changed the sign to read "SpongeBob and Toaster Corner"; "the least [they] could do for a little Toaster, who has done such big things!".
At the beginning of the closing credits, Carly Simon reprises in a live-action sequence the song "With a Few Good Friends", which originally appeared during the scene showing the building of the House at SpongeBob (and Toaster) Corner, before it ends with the music from the rest of the film.