This will be Cartoon Network's first original program to get a theatrical release since The Powerpuff Girls Movie, released in 2002.
Like many of Cartoon Network's films, it was initially set to be released as a made-for-television film, but was instead theatrically released on May 19, 2017 in the RealD 3D formats.
Finn and Jake, solving all the cases and events of the Mushroom War, but when the Lich attacks again their farmworld and the farmworld versions of the heroes, they must teamed up with heroes and save their world and stop the Lich and save their farmworld, with the help of Fionna and Cake, the gender-swapped versions of Finn and Jake created by Ice King.
- Jeremy Shada as Finn, Farmworld Finn
- John DiMaggio as Jake
- Hynden Walch as Princess Bubblegum
- Olivia Olson as Marceline
- Kristen Schaal as Jake Jr.
- Niki Yang as BMO
- Tom Kenny as Ice King
- Ron Perlman as the Lich
- Pendleton Ward as Lumpy Space Princess
- Steve Little as Peppermint Butler
- Madeleine Martin as Fionna
- Roz Ryan as Cake
The movie was first announced in February 2015 during the Cartoon Network upfront. Series creator Pendleton Ward announced on November 4, 2016 via Twitter that production of the movie has been completed. A trailer for the movie was shown at the 2016 Comic Con International event on January 6, 2017 and was later released online on January 7, 2017. Despite the movie being announced in November 2016 it began production in 2015.
During production of the fourth season, the network asked the creator if they'd like to do a fifty-minute special episode, Pendleton Ward turned it down and asked to do a movie instead, the network agreed. The idea was then put into development.
Ward confirmed that the movie is canon and is set in the middle of season seven and season eight.
The eighth season of Adventure Time was affected by the movie. It was set to have 40 episodes, but due to the production of the movie, only 31 were produced. Season eight will feature the regular 40 episodes per season.
Adventure Time: The Kingdom of Ooo was originally set to be released in North America as a made-for-television film in Fall 2017, while having a theatrical release in Europe. However, in December 2016 Cartoon Network announced that the film would be released theatrically. This was the first Cartoon Network film released theatrically in North America since The Powerpuff Girls Movie eight and a half years earlier in 2002.
The film premiered on May 5, 2017, at a special screening at Grauman's Chinese Theatre in Hollywood. Along with the special screening of the movie, Warner Bros. brought a balloon version of Finn and Jake to be part of the activities. The balloon version of Finn was owned by the Cartoon Network fans. The film was theatrically released on May 19, 2017, when it was also screened at the Warner Bros. Studios in Anaheim, California, a biennial convention for Warner Bros. fans.
The film was released on Blu-ray (2D and 3D), DVD and Digital HD on October 3, 2017. The DVD included extras such as deleted scenes, behind-the-scenes footage, audio commentaries, the three bonus shorts: Slumber Party Panic, Tree Trunks and The Enchiridion and the sneak peek of The Amazing World of Gumball: Movie.
The soundtrack for the film was released on May 2, 2017 by Warner Bros. Records, featuring three new songs "Make a Hero of You" and "Let it Go", and including the real-life song "This is War" by 30 Seconds to Mars, which was heard in the end credits.
- "Adventure Time Theme Song" - performed by Pendleton Ward
- "Make a Hero of You" - performed by John DiMaggio
- "Finn and Fionna" - performed by John DiMaggio and Roz Ryan
- "Let It Go" - performed by Jeremy Shada and Ron Perlman
- "This is War" - 30 Seconds to Mars
A video game featuring a plot set directly after the film, titled The Kingdom of Ooo: The Game, was released in North America on May 19, 2017 (the same day as the release of the film) for the Nintendo 3DS, Xbox 360 and PlayStation Vita. The game is published by Activision. A mobile game, titled Adventure Time: Finn on the Run, was released on May 31, 2017 for iOS and Android. It is an endless running game based on the film, featuring several mini games.
In February 2015, it was reported that a theatrical Adventure Time movie was being developed by Cartoon Network Studios, Frederator Films, Vertigo Entertainment, and Warner Animation Group. The film is being executive produced and written by Pendleton Ward, and produced by Roy Lee and Chris McKay. In October 2015, series producer Adam Muto confirmed that series creator Pendleton Ward is still currently "working on the premise" for the film, but that there was "nothing official to announce yet".
- The film was originally intended as the series finale, but Cartoon Network ordered more episodes of the series after the film's success, so Pendleton Ward resigned as Showrunner, with Graves taking Larry Leichter's Place.
- The film was in Normal 3D, Real D 3D, IMAX 3D, Digital 3D & XD 3D.
- This film was the of the successful films Of 2017.
- Being the 2nd theatrical film from Cartoon Network after The Powerpuff Girls Movie.
- The film has the same footage of the episodes, "The Lich", "Finn the Human", "Jake the Dog" and "Crossover".
- Lumpy Space Princess acts more antagonistic in the film.
- Main article: Adventure Time: The Kingdom of Ooo/Transcript
- Main article: Adventure Time: The Kingdom of Ooo/Trailer transcripts
- Main article: Adventure Time: The Kingdom of Ooo/Credits