The series follows Eiji Hino, who becomes Kamen Rider OOO after obtaining the power of the Core Medals, which are linked to three different animal species (the Hawk, Tiger, Cheetah, Stag Beetle, and Grasshopper) and grant him the ability to transform and use various powers.

The title OOO signifies the three medals that the main Kamen Rider uses to transform as well as being representative of the infinity symbol (

However, due to the 2011 Tōhoku earthquake and tsunami, the airing of this episode was postponed by one week to April 3, 2011.

For the 999th and 1000th episodes, various guest stars with the kanji for thousand (千, chi) in their name were featured: Chiaki, Chisato Morishita, Chinatsu Wakatsuki, and the owarai duo Harisenbon (sen also being Japanese for 1000).

The mysterious Kougami Foundation approaches Eiji and begins assisting him in his fight against the Greeed, though their true motives are not clear.

Kamen Rider OOO Wonderful the Movie: The Shogun and the 21 Core Medals (劇場版 仮面ライダーオーズ WONDERFUL 将軍と21のコアメダル, Gekijōban Kamen Raidā Ōzu Wandāfuru Shōgun to Nijū-ichi no Koa Medaru)[10] is the main theatrical release for Kamen Rider OOO, released on August 6, 2011, alongside Kaizoku Sentai Gokaiger the Movie: The Flying Ghost Ship.

[14][15] Shu Watanabe and Riho Takada had reprised their roles as Eiji Hino and Hina Izumi, while Asaya Kimijima and Hiroaki Iwanaga reprised their roles voicing Kamen Rider Birth and Kamen Rider Birth Prototype respectively.

A Movie War film, titled Kamen Rider Heisei Generations Final: Build & Ex-Aid with Legend Rider (仮面ライダー平成ジェネレーションズ FINAL ビルド&エグゼイドwithレジェンドライダー, Kamen Raidā Heisei Jenerēshonzu Fainaru Birudo Ando Eguzeido Wizu Rejendo Raidā) was released on December 9, 2017.

Kamen Rider OOO Hyper Battle DVD: Quiz, Dance, and Takagarooba!?

The DVD featured the Kangaroo Medal, which was used by Kamen Rider OOO to transform either his arms or legs to have kangaroo-themed powers.

The first soundtrack for Kamen Rider OOO was released on November 17, 2010; it includes an edit of the series' opening theme "Anything Goes!".

DJ HURRY KENN announced on Twitter that Kamen Rider OOO's "final song" would be recorded on July 18, 2011.