Set after the events of Kingdom Hearts 3D: Dream Drop Distance, returning protagonist Sora is joined by Donald Duck, Goofy, King Mickey, and Riku in their search for seven guardians of light as they attempt to thwart Xehanort's plan to bring about a second Keyblade War.

[13] Additionally, the development team "always want to try something new", taking previously introduced mechanics and making small "tweak[s]" to them so they are customized for Kingdom Hearts III.

[21] In addition to these traditional "smaller" enemies, the player faces giant bosses, which give "Sora greater freedom of movement and room to experiment with attacks—including the new theme-park-ride summon attacks,"[13] known as "Attraction Flow".

[30] The Keyblade transformations active the various "Formchanges"[25]–Power, Guard,[34][35] Magic,[35] and Speed–[35] and change Sora's outfit,[35] similarly to the "Drive Form" mechanic in Kingdom Hearts II.

[44] Kingdom Hearts III also has a "Memory Archive" feature, which has several short films explaining the basic story elements of the series from the previous games.

[31] The story opens with the final scenes of Kingdom Hearts 0.2: Birth by Sleep – A Fragmentary Passage, and serves as a conclusion of the "Dark Seeker/Xehanort Saga" that occurs in most preceding games.

[36] Kingdom Hearts III also introduces a new original character named Yozora, who features prominently in an in-universe video game commercial in the Toy Story world, and later in the secret ending.

Disney characters who serve as members of Sora's party include the returning Hercules and Jack Sparrow;[15][74] new to the series are Woody and Buzz Lightyear,[56] Sulley and Mike Wazowski,[41] Rapunzel and Flynn Rider,[75] Marshmallow,[76] and Baymax.

Discovering Master Eraqus's Keyblade on the Destiny Islands, Sora uses it to enter the realm of darkness and aid his friends, defeating and restoring Aqua.

Sustained by Kairi's power, Sora awakens in a limbo realm called the Final World, where a Chirithy guides him in restoring his fragmented body.

After Square Enix finished development of Kingdom Hearts II: Final Mix, Tetsuya Nomura was approached by Disney, who expressed interest in a sequel.

[85] He later noted that Kingdom Hearts III would not see a release until after 2012, due to his continuing work on Final Fantasy XV, regardless of the tenth anniversary of the series occurring in that year.

[18][47] Series producer Shinji Hashimoto stated in September 2013 that since Nomura was director of both Kingdom Hearts III and Final Fantasy XV, it was expected that there would be a significant gap between the release of the two, "as [they] want each game to be perfect in terms of quality."

[99] In January 2015, Yasue revealed that working on HD 2.5 Remix simultaneously allowed the developers to learn all the best qualities from the series to aid in creating III.

[102] Nomura noted the long development was due to internal Square Enix corporate decisions, such as changing to the Unreal Engine 4 about a year into the game's development, which led to "extensive delays" and "a bit of time that needed to be rewinded and started over", and "certain timing and resources challenges within Square Enix", despite submitting and getting approved a plan for when more personal resources would be needed on the project.

[45] A selection of the mini-games were made available in Union χ in its "χ3" mode added in September 2018, which enables players to obtain the "Starlight" Keyblade in Kingdom Hearts III by completing certain objectives.

[109] Nomura revealed the Tangled world was one of the first determined to be in the game, as the development team wanted to include Rapunzel due to her strong personality and her hair, finding it fitting for the gameplay.

"[60] In June 2013, Nomura discussed the updated visuals, saying that the development team tried to return the character's texture to the original "paintbrush art from Disney productions".

He added that the basis for the resulting design is a mix between Sora's costumes for Kingdom Hearts II and Dream Drop Distance, one that is "a lot more sleek and sporty" in order to make him look more acrobatic.

Speaking specifically to interactions such as this with Rapunzel, Yasue said "finding and activating these moments builds trust with" her and can lead "to additional combat scenarios and treasure opportunities".

[124] As with the first two main Kingdom Hearts games, it has a theme song written and performed by Hikaru Utada, titled "Chikai" in Japanese and "Don't Think Twice" in English.

[129] Kingdom Hearts III only features English and Japanese voice acting and lip syncing, despite previous entries in the series having dubbing in other languages.

[56] Almost a year later, at an additional performance of the Kingdom Hearts Orchestra World Tour in Los Angeles, the game's North American release date was revealed to be January 29, 2019.

[146] A limited edition Kingdom Hearts III-themed PlayStation 4 Pro and DualShock 4 controller was released on January 29, 2019, exclusive to GameStop and EB Games in North America.

Ultimate and the 20th anniversary of the Kingdom Hearts franchise, and was released on the Nintendo eShop alongside cloud versions of the 1.5+2.5 HD Remix and 2.8: Final Chapter Prologue collections on February 10, 2022.

[165] Critical response to the narrative was mixed, with both RPGamer and GamesRadar finding the visuals of the Pirates of the Caribbean world awkward to watch due to Square's attempt to emulate realism.

[155][167][157] GameRevolution and EGM found that the Organization XIII as final stage villains made the narrative accessible to most gamers and praised the voice acting, especially Haley Joel Osment as Sora, and Richard Epcar and Paul St. Peter as Xehanort's alter egos.

"[159] In its debut week, the game topped the EMEAA (Europe, Middle East, Africa, Asia) charts, in terms of both unit sales and gross revenue.

[204] GameSpot and GameInformer called it a director's cut, with the former praising the inclusion of Riku, Aqua and Kairi as playable characters, but criticizing how the main fighting area, the Keyblade Graveyard, had poor design in contrast to other worlds previously seen in the franchise.

[206] In regards to the narrative, GameInformer found it disappointing as, while the game allows the player to explore a new area and see more Final Fantasy characters, they are not properly followed.