In the vibrant underwater world of Bikini Bottom, restaurateur Eugene Krabs [clancy-brown] takes on an ambitious challenge by launching a second branch of his beloved establishment, the Krusty Krab. Eager to step into the role of manager, the ever-zealous fry cook SpongeBob SquarePants [carolyn-lawrence] is heartbroken when he is passed over for the position in favor of the lackluster cashier Squidward Tentacles. Krabs believes that Squidward's worldliness makes him the better candidate. After this setback, a despondent SpongeBob seeks solace with his loyal friend Patrick Star. Together, they indulge in a binge of ice cream at the local Goofy Goober parlor.
Meanwhile, a nefarious plot is brewing as Plankton, the scheming proprietor of the failing Chum Bucket, hatches a devious plan. He deceitfully steals King Neptune's crown, sends it to Shell City, and frames Krabs for the theft. Unwittingly aiding in the deception, SpongeBob inadvertently covers Krabs in ice cream, solidifying the perception of guilt in Neptune's eyes.
The furious king confronts Krabs at the Krusty Krab 2, convinced of his wrongdoing. With the threat of Neptune's wrath looming large, he freezes Krabs in place and gives SpongeBob a daunting task: recover the crown from Shell City within six days, or face execution for Krabs. Mindy, Neptune's daughter, warns SpongeBob about the lurking danger of the "Cyclops" in Shell City.
Determined to save the day, SpongeBob and Patrick embark on their journey in the Patty Wagon, a quirky vehicle shaped like a Krabby Patty hidden beneath the restaurant. However, their adventure is cut short when they find themselves carjacked during their trip. They chase the thief to a dingy bar, where their bumbling antics result in chaos, but they eventually reclaim their beloved vehicle.
In a parallel plot, Plankton seizes the opportunity to abscond with the secret Krabby Patty formula from the frozen Krabs and begins to sell his own inferior version at the Chum Bucket. He employs mind-control helmets, brainwashing innocent customers into doing his bidding. As a result, Plankton transforms Bikini Bottom into Planktopolis, establishing a reign of terror with the help of a hired hitman named Dennis to thwart SpongeBob's return with the crown.
As SpongeBob and Patrick navigate a treacherous ravine, their Patty Wagon meets an untimely end, plunging them into despair. In their moment of need, Mindy appears, gifting them with an unconventional confidence boost—a pair of whimsical seaweed mustaches. Transformed into what they believe are “men,” the duo finds the courage to brave the formidable trench, celebrating their triumph as they overcome the challenges before them. However, their relief is short-lived as they face Dennis, who quickly disposes of their makeshift disguises. Just when hope seems lost, a massive boot belonging to the mysterious Cyclops (a human diver in disguise) crashes down, capturing SpongeBob and Patrick.
Their suffering intensifies as they end up trapped in a fishbowl under the relentless light of the Cyclops' lamp. Just as despair envelops them, their tears short-circuit the lamp, awakening the lifeless sea creatures around them. The ensuing chaos provides the perfect opportunity for SpongeBob and Patrick to escape, emerging from their ordeal with newfound confidence.
Upon their victorious return to Bikini Bottom, they have a series of bizarre encounters: they retrieve the crown, outwit Dennis aboard David Hasselhoff’s catamaran, and disrupt Neptune's plan to execute Krabs. With Plankton's mind-control helmet now in effect, SpongeBob and Patrick confront an army of brainwashed citizens. Fearless, SpongeBob taps into his musical talents, performing "Goofy Goober Rock" to shatter the hypnotic grip on Neptune and the citizens of Bikini Bottom. Ultimately, Plankton is caught, Krabs is freed from his icy trap, and SpongeBob claims the promotion to manager of the Krusty Krab 2.
In a delightful post-credits moment, an usher leads the pirates out of the theater, marking the close of this adventure-filled cinematic experience.
