Winners of the 2012 Seiun Awards, the Japanese equivalent to the Hugo Awards, were announced at Varicon 2012, the 51st Japanese national SF convention, held July 7-8, 2012 in Yubari City, Hokkaido, Japan.
- Best Japanese Novel: Tengoku and Zigoku, Yasumi Kobayashi (Hayakawa)
- Best Japanese Short Story: “The Singing Submarine and Peer-Peer Douga”, Hosuke Nojiri (Hayakawa)
- Best Translated Novel: The Windup Girl, Paolo Bacigalupi, translated by Kazue Tanaka & Hiroshi Kaneko (Hayakawa)
- Best Translated Short Story: “The Lifecycle of Software Objects”, Ted Chiang, translated by Nozomi Ohmori (Hayakawa)
- Best Dramatic Presentation: Puella Magi Madoka Magica (Shimbō Akiyuki/Shaft Inc.)
- Best Comic: Gundam: The Origin, Yoshikazu Yasuhiko (Kadokawa Shoten)
- Best Artist: Naohiro Washio
- Best Non-fiction: Hideo Azuma Soutokushu [The Hideo Azuma Omnibus] (Kawade Shobo Shinsha)
There were no nominations for the Best Event category, so no award was given.