Watanabe was born in Ōtawara, Tochigi Prefecture, and attended the Japan Institute of the Moving Image.
[1] He studied under Daisuke Tengan (son of Shohei Imamura) and in 2008 won the grand prize at the 9th Fuji Film Lovers Festival with his graduation film, A Light Pig of August.
[1][4] His 2016 film, Poolsideman, won the Japanese Cinema Splash Best Picture Award at the 29th Tokyo International Film Festival[5] as well as the Nippon Visions Jury Award at the 2017 Nippon Connection.
[6][7] In his review of Poolsideman, critic Mark Schilling wrote of Watanabe's early films that "Hirobumi Watanabe has created a unique cinematic world" with films "all shot in black-and-white in Watanabe’s native Tochigi Prefecture, with music by younger brother Yuji and cinematography by Woohyun Bang.
All focus on socially marginalized men with lives that range from the aimless to the mundane.