The anime will premiere with a television special on TV Tokyo, TV Osaka, and TV Aichi on April 2. The anime's website describes the April 2 airing in Japan as the "broadcast premiere commemorative special."
The main cast members are reprising their roles in the second season:
- Makoto Furukawa as Saitama
- Kaito Ishikawa as Genos
- Yuuki Kaji as Onsoku no Sonic (Speed-o'-Sound Sonic)
- Aoi Yūki as Senritsu no Tatsumaki (Terrible Tornado)
- Kazuhiro Yamaji as Silverfang
- Kenjiro Tsuda as Atomic Samurai
- Minami Takayama as Dōtei (Child Emperor)
- Tesshō Genda as Metal Knight
- Hiroki Yasumoto as King
- Takahiro Sakurai as Zombieman
- Yōji Ueda as Kudō Kishi (Drive Knight)
- Daisuke Namikawa as Butagami (Pig God)
- Satoshi Hino as Chōgōkin Kurobikari (Superalloy Blackluster)
- Yūji Ueda as Banken-man (Watchdog Man)
- Kousuke Toriumi as Senkō no Flash (Flashy Flash)
- Katsuyuki Konishi as Tank-top Master
- Wataru Hatano as Kinzoku Bat (Metal Bat)
- Masaya Onosaka as Puri-Puri Prisoner
- Mamoru Miyano as Handsome Kamen Amai Mask
- Saori Hayami as Jigoku no Fubuki (Hellish Blizzard)
- Yūichi Nakamura as Mumen Rider
Chikara Sakurai (Magimoji Rurumo, episode director for Naruto Shippūden) is replacing Shingo Natsume to direct the season at J.C. Staff (Food Wars! Shokugeki no Soma, Children of the Whales). Madhouse animated the first season.
Yoshikazu Iwanami (Girls und Panzer, JoJo's Bizarre Adventure) is replacing Shoji Hata as sound director. Chikashi Kubota (Corpse Princess: Aka, FLCL 2) is returning to design the characters, and Tomohiro Suzuki (ACCA: 13-Territory Inspection Dept.) is again in charge of series composition. Makoto Miyazaki (Triage X, Dragon Crisis!) is also returning to compose the music. JAM Project is once again performing the opening theme song "Seijaku no Apostle." Makoto Furukawa, the voice actor for protagonist Saitama, will perform the ending theme song "Chizu ga Nakutemo Modoru kara" (Even Without a Map, I'll Return).
Madhouse and director Shingo Natsume's first 12-episode anime season based on ONE and Yuusuke Murata's One-Punch Man manga aired in Japan from October-December 2015. Animax Asia aired the anime in Southeast Asia in September 2016, and the now-defunct Daisuki streaming service also offered the anime in selected Asian countries.