An anime adaptation was announced in the 15th issue of Weekly Young Jump on March 10, 2015. The series' first season was directed by Shingo Natsume at Madhouse and written by Tomohiro Suzuki. The series also features character designs by Chikashi Kubota, who also serves as chief animation director, music by Makoto Miyazaki and art design by Shigemi Ikeda and Yukiko Maruyama. Ken Hashimoto serves as the series color key artist, Akane Fushihara is the director of photography and Kashiko Kimura serves as the series editor, and Shoji Hata does sound design. The opening theme song is "The Hero!! ~Ikareru Ken ni Honō o Tsukero~" (THE HERO!! ～怒れる拳に火をつけろ～, "The Hero!! Set Fire to the Furious Fist") by JAM Project, and the closing theme is "Hoshi Yori Saki ni Mitsukete Ageru" (星より先に見つけてあげる, "I'll Find It Before the Stars for You") by Hiroko Moriguchi.

One-Punch Man's first season aired in Japan between October 5, 2015 and December 21, 2015 on TV Tokyo, airing at later dates on TVO, TVQ, KBS, BS Japan, and AT-X,and ran for 12 episodes. The seasonstreamed on Niconico and was simulcast on Hulu, Daisuki, and Viz Media's Neon Alley service. A preview screening was held in the Saitama City Cultural Center on September 6, 2015. The series is licensed by Viz Media in North America, and by Kaze UK in the United

Kingdom. An original video animation was released with the tenth manga volume on December 4, 2015.Additional OVA episodes are included with Blu-ray Disc & DVD volumes of the season, the first of which was released on December 24, 2015.

Murata announced in the last weeks of the first season's airing schedule that he is working on making a second season a reality, but has not confirmed it is in development as of December 2015