SpongeBob and Patrick embark on a rescue mission to save Gary, who has been "snailnapped" by Poseidon, traveling to the Lost City of Atlantic City. The movie will also reveal the origin of SpongeBob and Gary's meeting for the first time as children.
- Tom Kenny as SpongeBob SquarePants and Gary the Snail
- Bill Fagerbakke as Patrick Star
- Clancy Brown as Eugene H. Krabs
- Mr. Lawrence as Sheldon J. Plankton
- Rodger Bumpass as Squidward Tentacles
- Carolyn Lawrence as Sandy Cheeks
In a February 2015 interview discussing The SpongeBob Movie: Sponge Out of Water's success at the box office, Megan Colligan, president of worldwide distribution and marketing at Paramount Pictures, stated the possibility of a third film was "a good bet." Later in 2015, it was revealed that Paramount was developing sequels to its franchises, including another SpongeBob film.
The film was initially scheduled for release in 2019, before being postponed to 2020. By January 2016, Jonathan Aibel and Glenn Berger had been chosen to write the film.
In March 2017, Paramount president Marc Evans announced that the studio would work closely with Viacom on its TV brands, including the SpongeBob film. During the same month, Yahoo! Entertainment stated that the film would be titled The SpongeBob Movie.
In April 2018, the film's official title was revealed as The SpongeBob Movie: It's a Wonderful Sponge, and SpongeBob co-developer Tim Hill was announced as director and writer for the film. It was reported later in the year that the film would be written by Aibel, Berger, and Michael Kvamme. The principal cast are all expected to reprise the roles as their respective characters from the series and the previous films. In October 2018, Paramount Animation president Mireille Soria revealed the plot for the film. Hans Zimmer was announced as the composer for the film, while Paris and Montreal-based Mikros Image would handle animation, which would be created entirely through computer animation.
On June 12, 2019, it was announced that Reggie Watts and Awkwafina were added to the cast while Cyndi Lauper and Rob Hyman, who wrote a song for The SpongeBob Musical, would be writing original songs for the film. It was also announced that Mia Michaels would be choreographing and Ali Dee Theodore would add an original song for the film. The next day, Snoop Dogg announced that he would be in the film.
On November 12, 2019, it was revealed that the film's title was changed from It's a Wonderful Sponge to Sponge on the Run, along with the casting of Keanu Reeves.
On January 22, 2019, it was confirmed that production on the film had officially begun. The film will include live-action sequences, with Larry Fong as the film's cinematographer. Unlike the previous films the animated sequences of the film will be computer-animated.
The SpongeBob Movie: Sponge on the Run was originally scheduled to be theatrically released on February 9, 2019. It was then was pushed back to August 2, 2019, before being delayed nearly a year to July 31, 2020. It was moved four more times: to July 17, 2020, May 22, 2020, July 3, and finally August 7, 2020. In June 2020, it was announced that the film's theatrical release had been cancelled and it would instead go straight to digital via CBS All Access in early 2021.